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Microsoft XML Core Services (MSXML) are set of services that allow applications written in JScript, VBScript, and Microsoft development tools to build Windows-native XML-based applications. It supports XML 1.0, DOM, SAX, an XSLT 1.0 processor, XML schema support including XSD and XDR, as well as other XML-related technologies.

Overview

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All MSXML products are similar in that they are exposed programmatically as OLE Automation (a subset of COM) components. Developers can program against MSXML components from C, C++ or from Active Scripting languages such as JScript and VBScript. Managed .NET Interop with MSXML COM components is not supported nor recommended.[1]

As with all COM components, an MSXML object is programmatically instantiated by CLSID or ProgID. Each version of MSXML exposes its own set of CLSID's and ProgIDs. For example, to create an MSXML 6.0 DOMDocument object, which exposes the IXmlDomDocument,[2] IXmlDomDocument2,[3] and IXmlDomDocument3[4] COM interfaces, the ProgID "MSXML2.DOMDocument.6.0" must be used.

MSXML also supports version-independent ProgIDs. Version-independent ProgIDs do not have a version number associated with them. For example, "Microsoft.XMLHTTP". These ProgIDs were first introduced in MSXML 1.0, however are currently mapped to MSXML 3.0 objects and the msxml3.dll.

Different versions of MSXML support slightly different sets of functionality. For example, while MSXML 3.0 supports only XDR schemas, it does not support XSD schemas. MSXML 4.0, MSXML 5.0, and MSXML 6.0 support XSD schemas. However, MSXML 6.0 does not support XDR schemas. Support for XML Digital Signatures is provided only by MSXML 5.0. For new XML-related software development, Microsoft recommends[5] using MSXML 6.0 or its lightweight cousin, XmlLite, for native code-only projects.[6]

Versions

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MSXML is a collection of distinct products, released and supported by Microsoft. The product versions can be enumerated as follows:[7]

Current

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  • MSXML 6.0 MSXML6 is the latest MSXML product from Microsoft, and (along with MSXML3) is shipped with Microsoft SQL Server 2005, Visual Studio 2005, .NET Framework 3.0, as well as Windows XP Service Pack 3, Windows Vista and every subsequent versions of Windows up to Windows 11. It also has support for native 64-bit environments. It is an upgrade but not replacement for versions 3 and 4 as they still provide legacy features not supported in version 6. Version 6, 4, and 3 may all be installed and running concurrently. MSXML 6 is not supported on Windows 9x. Windows XP SP3 includes MSXML 6.0 SP2.
  • MSXML 3.0 MSXML3 is a current MSXML product, represented by msxml3.dll. MSXML 3.0 SP2 first shipped with Windows XP, Internet Explorer 6.0 and MDAC 2.7. Windows XP SP2 includes MSXML 3.0 SP5 as part of MDAC 2.81. Windows 2000 SP4 also ships with MSXML 3.0. By default, Internet Explorer version 6.0, 7.0 and 8.0 use MSXML 3 to parse XML documents loaded in a window. MSXML 3.0 SP7 is the last supported version for Windows 95. Windows XP SP3 includes MSXML 3.0 SP9. Windows Vista also includes MSXML 3.0 (SP10).

Obsolete

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  • MSXML 5.0 MSXML5 was a binary developed specifically for Microsoft Office. It originally shipped with Office 2003 and also ships with Office 2007. Microsoft has not released documentation for this version because Microsoft considers MSXML 5 an internal/integrated component of Office 2003. MSXML 5 is not included in Office 2010.[8]
  • MSXML 4.0 MSXML4 was shipped as an independent, downloadable SDK targeted at independent software vendors and third parties. It is an upgrade for, but not a replacement to MSXML3 as version 3 still provides legacy features. There is no 64-bit version offered, although the 32-bit version was supported for 32-bit processes on 64-bit operating systems. Versions 4 and 3 may be run concurrently. MSXML 4.0 SP3 is the most recent version released in March 2009, SP2 support expired in April 2010,[9] and MSXML 4.0 SP3 expired in April 2014.[10]
  • MSXML 2.6 This is an early version of MSXML, and is represented by msxml2.dll. This product is no longer supported by Microsoft, and the CLSIDs and ProgIDs it exposes have been subsumed by MSXML 3.0. MSXML 2.6 shipped with Microsoft SQL Server 2000 and MDAC 2.6. The last version for all platforms was released as KB887606.
  • MSXML 2.5 This is an early version of MSXML, and is represented by msxml.dll. This version is also no longer supported by Microsoft, and the CLSIDs and ProgIDs it exposes have been subsumed by MSXML 3.0. MSXML 2.5 shipped with Windows 2000 as part of Internet Explorer 5.01 and MDAC 2.5.
  • MSXML 2.0a This version shipped with Internet Explorer 5.0. No longer supported.
  • MSXML 1.0 This version shipped with Internet Explorer 4.0. No longer supported.

See also

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References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia

MSXML

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Microsoft XML Core Services (MSXML) is a software library developed by that provides a set of components and APIs for processing, parsing, and manipulating XML documents in Windows-based applications. It enables developers to build high-performance, interoperable XML applications compliant with the XML 1.0 recommendation and various W3C standards. MSXML has been integral to products since its inception, supporting features like data exchange, document transformation, and schema validation across desktop, server, and web environments. The history of MSXML began with version 1.0, released in 1998 as part of 4.0, providing initial support for XML parsing and basic DOM manipulation. Subsequent versions evolved to address growing XML standards and application needs, with MSXML 3.0 (2000) introducing key enhancements like 1.0 and XPath 1.0 compliance, server-safe HTTP handling, and SAX2 support, making it broadly deployed across Windows operating systems. MSXML 4.0 (2002) added XML Schema Definition (XSD) support, Schema Object Model (SOM), and improved performance for XSLT processing (up to 8 times faster), though it is no longer supported as of April 2014. MSXML 5.0 (2003), primarily bundled with and 2007, introduced XML digital signatures and DOM node validation but is recommended only for Office-specific use. The current version, MSXML 6.0 (2006), with ongoing security updates as part of Windows support (as of 2025), ships with SP3 and later, offering the highest W3C compliance, enhanced security (e.g., disabled DTDs and inline schemas by default), and removal of deprecated features like XDR schema support, positioning it as the recommended choice for new COM-based development, while System.Xml is preferred for .NET applications.
VersionRelease YearKey Ships WithSupport StatusNotable Additions/Changes
1.01998Internet Explorer 4.0UnsupportedBasic XML parsing and DOM.
2.0–2.61999–2000IE 5.0–5.01, MDAC 2.5–2.6, SQL Server 2000UnsupportedIncremental improvements; subsumed by 3.0.
3.02000All supported Windows OSSupported (legacy)XSLT/XPath 1.0, SAX2, namespace support in DOM queries.
4.02002Web releaseEnded April 2014XSD/SOM support, faster XSLT, side-by-side installation.
5.02003Office 2003/2007Supported (Office only)XML digital signatures, DOM validation/import.
6.02006Windows XP SP3+, Vista+SupportedImproved security/compliance, removed XDR/digital signatures.
MSXML's core features include (DOM) for hierarchical XML access, (SAX) for event-based streaming parsing, XSD for schema validation, and for transformations, all designed for efficient handling of large XML datasets. It supports helper APIs for XML namespaces, HTTP data retrieval via WinHTTP, and in later versions, advanced schema caching and attribute normalization for better performance and standards adherence. Security is a focus in MSXML 6.0, with mitigations against vulnerabilities like XML external entity attacks through default disabling of certain parsing options. In practice, MSXML is invoked via COM interfaces in languages like C++, , or .NET through interop, allowing integration into applications for tasks such as web services, data binding, and processing. Developers can reference specific using ProgIDs (e.g., "Msxml2.DOMDocument.6.0") to ensure compatibility, and it is redistributable with applications or installable via Windows updates. For optimal reliability, recommends upgrading legacy installations to MSXML 6.0, except in contexts where version 5.0 may persist.

Introduction

Definition and Purpose

XML Core Services () is a set of COM-based components developed by for parsing, validating, and transforming XML documents in Windows-based applications. It implements a comprehensive suite of W3C-compliant APIs that support core XML processing tasks, enabling developers to handle structured data efficiently without relying on external libraries. As a native (COM) solution, integrates seamlessly with the Windows ecosystem, allowing instantiation via CLSIDs or ProgIDs for programmatic access. The primary purpose of MSXML is to facilitate the creation of high-performance, interoperable applications that leverage XML for data handling and exchange. It supports development in scripting languages such as and , as well as compiled environments like and C++, providing interfaces for broad compatibility. By offering robust XML manipulation capabilities, MSXML ensures that applications can process and exchange XML data reliably across diverse systems. Key use cases for MSXML include XML data exchange to promote between applications, integration in web services for server-side processing, and document manipulation in both client and web environments. Developers commonly employ it to parse incoming XML streams, apply transformations for output formatting, and validate documents against XML schemas or DTDs to maintain . In contrast to the .NET Framework's System.Xml namespace, which provides managed classes optimized for .NET applications, MSXML operates as native COM/OLE Automation components tailored for legacy systems and unmanaged code. This design makes MSXML particularly valuable in scenarios requiring direct integration or compatibility with older development paradigms.

Key Components

MSXML is composed of several primary components that enable core XML processing functionalities. The IXMLDOMDocument interface serves as the central component for (DOM) manipulation, representing the root of the XML document tree and implementing essential DOM methods for parsing, loading, and navigating XML structures. The IXSLProcessor interface handles (XSLT), facilitating the conversion of XML documents into other formats such as or different XML structures through asynchronous processing capabilities. Complementing these, the IXMLSchemaCache, also known as IXMLDOMSchemaCollection, manages schema validation by caching XML Schema Definition (XSD) files for reuse across multiple documents, ensuring efficient and thread-safe validation of XML instances against predefined schemas. Supporting these primary elements are additional components that extend MSXML's utility for event-driven and network interactions. The SAX reader, implemented via the IXMLReader interface, provides a streaming, non-caching approach to XML , ideal for processing large documents without full memory loading by delivering events as the parser progresses through the XML stream. The HTTP requestor, accessible through the IXMLHTTPRequest interface (commonly known as XMLHTTP), enables applications to send HTTP requests for XML data retrieval, handling responses and integrating them directly into the DOM for further processing. Schema collections, managed by the IXMLSchemaCache, further support validation workflows by allowing developers to add, remove, and query cached schemas dynamically. All MSXML components are exposed as (COM) objects, allowing instantiation in various programming environments such as , , or C++. Developers access them using version-specific ProgIDs, for example "MSXML2.DOMDocument.6.0" for the DOMDocument object in MSXML 6.0, or through Class Identifiers (CLSIDs) like {88D96A05-F192-11D4-A65F-0040963251E5} for precise binding in code. This COM-based design ensures compatibility with Windows applications and scripting hosts. A key architectural feature of MSXML is its support for side-by-side installation, which permits multiple versions—such as MSXML 3.0, 4.0, 5.0, and 6.0—to coexist on the same system without conflicts, using distinct DLLs and registry entries to maintain isolation and for legacy applications.

History

Origins and Early Development

began developing MSXML in early 1997 as part of its efforts to integrate support for the emerging Extensible Markup Language (XML) standard into 4.0, aiming to enable structured data exchange and web content innovation such as Active Channels using XML-based Channel Definition Format (CDF) files. The company had co-founded the (W3C) XML working group in July 1996, contributing to the specification's evolution through multiple drafts released between 1996 and 1997. MSXML 1.0 was initially released in September 1997, bundled with 4.0 for Windows, providing basic XML parsing capabilities through a (COM) interface that allowed integration with scripting languages like and in environments such as (ASP). This timing positioned MSXML as an early implementation ahead of the W3C's XML 1.0 Recommendation finalized in February 1998, reflecting Microsoft's proactive response to the standard's development for enhancing web and server-side applications. Early versions of MSXML faced challenges with standards compliance, offering only partial support for XML features and prioritizing Microsoft's proprietary XSL patterns—based on early W3C XSL working drafts—over the full emerging W3C specifications for transformations and querying. These limitations were driven by the rapid evolution of XML technologies and the need for performant, lightweight parsing in browser and scripting contexts, though they restricted broader interoperability until subsequent releases.

Major Releases and Evolution

MSXML 2.0, released in 1999, marked the initial major advancement in Microsoft's XML processing capabilities, shipping alongside 5.0 to provide foundational support for XML in web applications. This version introduced basic XSL transformations and compliance with DOM Level 1, enabling developers to parse and manipulate XML documents within browser environments. However, it remained tightly coupled to , limiting its use to web-centric scenarios. The transition to MSXML 3.0 in 2000 represented a pivotal shift, with releasing it as a standalone component to promote wider adoption beyond the browser. Key enhancements included full compliance with 1.0 and 1.0 standards, alongside XML 1.0 and DOM Level 1, facilitating more robust querying and transformation of XML data. This version's broad deployment across Windows operating systems underscored a growing emphasis on and legacy support. Subsequent releases further evolved MSXML toward enterprise applications. MSXML 4.0, introduced in 2002, added support for Definition (XSD) and improved performance through features like the Schema Object Model, targeting server-side and developer toolkit integrations such as BizTalk Server. MSXML 5.0, released in 2003 and bundled with and 2007, focused on Office-specific enhancements like XML digital signatures. By 2006, MSXML 6.0 emerged as a standards-focused iteration, enhancing W3C compliance, .NET compatibility, and security measures like schema caching, while integrating with products like SQL Server 2005 for data processing workflows. This progression reflected a strategic move from browser-bound tools to secure, high-performance solutions for enterprise environments. After MSXML 6.0, Microsoft entered , with no new major versions developed since the mid-2000s, prioritizing security updates and backward compatibility over innovation.

Technical Overview

Architecture and APIs

MSXML is built on the (COM) and OLE Automation framework, which facilitates access from multiple programming languages including C++, , and scripting environments like and . This design allows developers to instantiate MSXML objects through standard COM mechanisms, such as CoCreateInstance, enabling seamless integration in both native and managed applications. The library is distributed as dynamic-link libraries (DLLs), with versions implemented in files like msxml3.dll, msxml4.dll, msxml5.dll, and msxml6.dll, which are typically installed in the Windows system directory for system-wide availability. These DLLs support thread-safe operations through specialized objects, such as the FreeThreadedDOMDocument, which incorporates API-level locking and thread-safe to handle concurrent access without external synchronization.)) The core APIs revolve around a hierarchy of interfaces for XML processing. The Document Object Model (DOM) is exposed primarily through the IXMLDOMNode interface, which serves as the base for navigating and manipulating the XML document tree, with derived interfaces like IXMLDOMElement, IXMLDOMAttribute, and IXMLDOMText providing specialized functionality for specific node types. For event-driven, streaming parsing to minimize memory usage, MSXML implements the (SAX) as an event-based model, where the parser generates callbacks via interfaces such as ISAXContentHandler for start/end elements, ISAXCharacters for text data, and ISAXErrorHandler for error notifications during sequential document traversal. Asynchronous resource loading, particularly for HTTP-based XML retrieval, is handled by the IXMLHttpRequest interface, which supports non-blocking operations through methods like open, send, and onreadystatechange events, allowing applications to continue execution while awaiting responses.) Memory management in MSXML follows the COM standard of reference counting, where each object maintains an internal count incremented via AddRef and decremented via ; when the count reaches zero, the object is automatically destroyed to free resources. As an unmanaged library, MSXML does not employ garbage collection, requiring developers to explicitly manage object lifetimes to prevent leaks, especially in long-running applications. This approach ensures predictable performance but demands careful handling of interface pointers across language boundaries.)) Extensibility is provided through callback interfaces for customization. Custom error handling is supported via the ISAXErrorHandler interface in SAX mode, allowing applications to implement methods like and fatalError to process parsing issues, or through the IXMLDOMParseError interface in DOM mode for retrieving detailed information including line numbers and reasons. Error details are further exposed via the standard COM IErrorInfo interface, which delivers formatted messages and HRESULT codes for integration with hosting environments. While schema resolution relies on built-in caching via IXMLDOMSchemaCollection, custom extensions for external resource handling can be achieved indirectly through managers or proxy configurations, though primary extensibility focuses on and event callbacks.)))

Supported Standards

MSXML implements the XML 1.0 specification (Fourth Edition) for full parsing of well-formed XML documents across all major versions, enabling comprehensive handling of XML syntax, entities, and character data as defined by the W3C recommendation. It also provides support for Namespaces in XML 1.0 (Third Edition), allowing qualified names and prefix declarations to avoid naming conflicts in XML documents. Through its (DOM), MSXML offers partial support for the XML Information Set (Infoset), modeling key information items such as elements, attributes, and text nodes, though with some limitations due to implementation-specific behaviors. For document manipulation, MSXML conforms to DOM Level 1 Core and DOM Level 2 Core specifications, supporting node creation, traversal, modification, and in a platform-independent manner. It additionally implements 2.0 for event-driven, sequential XML parsing, which facilitates memory-efficient processing by notifying applications of parsing events without building a full tree structure. These core standards ensure with W3C-defined XML processing models, though Microsoft introduces threading models (rental-threaded and free-threaded) as extensions to the DOM for enhanced concurrency in COM environments. In terms of querying and transformation, MSXML fully supports 1.0 for selecting nodes based on patterns and expressions, integrated into both DOM and operations. It also implements 1.0 for applying stylesheet-based transformations to XML documents, enabling output in formats like or other XML structures. For schema validation, early versions (MSXML 3.0 through 5.0) utilize the proprietary XML-Data Reduced (XDR) schema language, while later versions (MSXML 4.0 through 6.0) add compliance with Definition (XSD) 1.0 (Second Edition) for type-aware validation against W3C schemas.) Overall, MSXML adheres closely to these W3C recommendations but incorporates Microsoft-specific extensions, such as XDR and custom functions, to extend functionality beyond strict standards compliance.

Versions

Current Versions

MSXML 3.0, released in 2000, remains a supported version for legacy compatibility and is widely deployed across Microsoft operating systems. It supports XML-Data Reduced (XDR) schemas, XPath 1.0, and XSLT 1.0, enabling basic XML parsing and transformation capabilities suitable for older applications. This version is bundled with Windows XP through Windows 7, as well as Internet Explorer 6 through 8, ensuring broad availability without additional installation in many environments. The final major update, Service Pack 7 (SP7), was released in 2006, incorporating bug fixes and security patches to maintain stability for ongoing use, with subsequent security updates provided as part of OS support as of November 2025. MSXML 6.0, released in , represents the latest evolution in the supported MSXML lineup, offering enhanced performance, security, and standards compliance for modern XML processing. It fully supports Definition (XSD) schemas but removes support for the proprietary XDR schemas, aligning more closely with W3C recommendations. Unlike earlier versions, MSXML 6.0 is compatible with 64-bit architectures, making it suitable for contemporary systems. This version is bundled with .NET Framework 3.0 and later, SQL Server 2005 and subsequent releases, and onward, facilitating seamless integration in enterprise and development scenarios. 3 (SP3) introduced key security enhancements, including disabling Document Type Definitions (DTDs) and inline schemas by default to mitigate potential vulnerabilities. Deployment of both MSXML 3.0 and 6.0 occurs automatically through , ensuring users receive the latest patches without manual intervention. Support for MSXML 3.0 and 6.0 follows the support lifecycle of the underlying Windows operating systems, with updates provided as of November 2025. These versions support side-by-side installation, allowing multiple iterations to coexist on the same system for compatibility with diverse applications. For new development projects, recommends MSXML 6.0 due to its superior reliability, features, and alignment with current standards. Conversely, MSXML 3.0 is advised for maintaining compatibility with legacy browser-based or older software environments where newer versions may introduce breaking changes.

Obsolete Versions

MSXML versions 1.0 through 4.0 are considered obsolete and are no longer recommended for use in new or maintained applications due to their lack of ongoing support, unpatched vulnerabilities, and incompatibility with modern systems. These early releases played a crucial role in introducing XML processing capabilities to ecosystems, particularly in web browsers and during the late and early , but they have been superseded by more robust implementations. MSXML 5.0, while obsolete for general use, remains supported specifically for and 2007 applications. MSXML 1.0 and 2.x were initial releases bundled with 4.0 (1997) and 5.0 (1999), providing basic XML parsing and a COM-based (DOM) implementation without support for transformations. These versions focused on foundational XML handling for early but lacked advanced standards compliance and performance optimizations. They became unsupported in the early 2000s as shifted to more feature-rich parsers. MSXML 4.0, released in 2002 as a web-downloadable component, introduced Definition (XSD) support, enhanced parsing, and improved overall performance, making it suitable for server-side applications. It received updates through Service Pack 3 in 2009 and was integrated into products like Project Server 2003. However, mainstream support ended in April 2014, leaving it vulnerable to unpatched issues. MSXML 5.0, released in 2003 exclusively for and 2007, added support for XML Digital Signatures via a COM-based , enabling secure XML document signing in environments. As an -specific variant, it was undocumented for general-purpose use outside of applications and was phased out with the removal of support in Office 2010 and later versions for non-Office use. Common issues across these obsolete versions include unpatched security vulnerabilities, such as remote code execution flaws exploited via specially crafted XML content, and a lack of native 64-bit support, limiting their viability on contemporary hardware. For instance, post-2014 vulnerabilities in MSXML 4.0 remain unaddressed, posing risks in legacy deployments. Additionally, earlier versions like 3.0 and 4.0 relied on Microsoft-specific XML Data Reduced (XDR) schemas, which differ from the standard XSD format emphasized in later releases. For migration, developers should upgrade to MSXML 6.0, the current supported version, while auditing code for dependencies on XDR schemas and replacing them with XSD equivalents to ensure compatibility. This transition mitigates security risks and enables better integration with modern XML standards.

Features and Capabilities

Parsing and Document Object Model (DOM)

MSXML provides robust mechanisms for parsing XML documents, enabling developers to load and process structured data either synchronously or asynchronously. The primary parsing methods include load(), which retrieves and parses XML from a , file, or input stream, and loadXML(), which parses XML directly from a string. Both methods operate synchronously by default, constructing a complete (DOM) tree upon successful loading, but asynchronous loading can be enabled through properties like async on the IXMLDOMDocument interface, allowing non-blocking operations for large documents. These methods first ensure the XML is well-formed, checking for syntactic correctness according to XML 1.0 standards, but do not perform schema validation by default. For validation beyond , MSXML supports schema-based checking via the validate() method on the IXMLDOMDocument interface, which verifies the document against an associated (DTD) or (XDR in MSXML 3.0; XSD in MSXML 4.0 and later), or a pre-loaded schema collection. This run-time validation integrates seamlessly with the parsing process, raising errors if the document fails to conform to the specified . Developers can configure validation options by setting properties such as validateOnParse to true before loading, ensuring automatic schema enforcement during the initial parse. The DOM in MSXML represents parsed XML as a hierarchical, tree-based structure, with IXMLDOMDocument serving as the root node that encapsulates the entire document. This model implements the W3C (DOM) Level 1 Core specification, with extensions for additional functionality such as namespace support, providing a platform- and language-neutral interface for accessing and manipulating XML. Core components include IXMLDOMNode and its derived interfaces, such as IXMLDOMElement for elements, IXMLDOMAttribute for attributes, and IXMLDOMText for textual content, allowing traversal via methods like childNodes, parentNode, and attributes. Navigation and querying are facilitated by methods including selectNodes(), which returns a node list matching an XPath expression, and transformNode(), which applies an XSL stylesheet to generate output—though the latter is typically used post-parsing for data manipulation. As an alternative to the memory-intensive DOM, MSXML implements the (SAX) Version 2 for event-driven, streaming , ideal for processing large XML files without building a full in-memory tree. SAX operates sequentially, firing events such as startElement (triggered at the opening of an element tag) and endElement (at the closing tag) to registered content handlers, enabling low-memory consumption and forward-only access. Developers implement interfaces like IVBSAXContentHandler to respond to these events, processing data incrementally—such as extracting values during —without retaining the entire document structure. This approach contrasts with DOM by prioritizing performance in resource-constrained environments. Performance in MSXML's DOM parsing relies on an in-memory tree representation, which caches the full document structure for efficient and repeated queries, though this can lead to higher usage for very large files compared to SAX's streaming model. Error handling during parsing is managed through the IXMLDOMParseError interface, accessible via the parseError of IXMLDOMDocument, which captures details of the last error—including , , character position, file position, source text, and a descriptive reason—allowing precise diagnostics and recovery. In asynchronous scenarios, errors are reported via events like onreadystatechange, ensuring robust application handling.

Transformation and Querying (XSLT and XPath)

MSXML provides support for querying XML documents using 1.0, an expression language defined by the W3C for selecting nodes based on their position, type, or attributes. This support is available across MSXML versions starting from 3.0, enabling developers to navigate and extract data from the (DOM) efficiently. For instance, an expression such as /root/child[@attr='value'] can target a specific child element with a matching attribute value. The primary mechanism for XPath querying in MSXML is through the IXMLDOMNode interface's selectSingleNode and selectNodes methods, which evaluate the provided expression against the node and its descendants. The selectSingleNode method returns the first matching node as an IXMLDOMNode object, while selectNodes returns an IXMLDOMNodeList containing all matches. These methods internally compile the expression for reuse within the same evaluation context, optimizing performance for repeated queries on the same document. For XML transformations, MSXML implements XSLT 1.0, allowing rule-based processing of XML input to generate output in formats such as HTML, XML, or plain text. This is handled via the IXSLProcessor interface, which loads and applies XSLT stylesheets to an input DOM document. The processor uses template rules defined in the stylesheet, invoking elements like <xsl:apply-templates> to match patterns and generate output based on XPath selections. Developers can specify the output method using the <xsl:output> element in the stylesheet, directing the result to HTML for web display, XML for structured data, or text for simple extraction. Integration of XPath and XSLT in MSXML occurs seamlessly through the DOM, where a loaded XML document serves as input for transformations. The transformNode method on IXMLDOMDocument applies a stylesheet to the entire document and returns the transformed string directly. For enhanced performance in scenarios involving multiple transformations with the same stylesheet, MSXML supports template caching via the IXSLTemplate interface, which compiles the stylesheet once and allows creation of reusable IXSLProcessor instances. This caching reduces compilation overhead, making it suitable for server-side applications processing batches of XML inputs. MSXML's XSLT implementation includes Microsoft-specific extensions to extend functionality beyond the XSLT 1.0 standard, such as the msxsl:node-set() function, which converts a result tree fragment into a node-set for further processing. However, it does not support 2.0 or later versions, limiting advanced features like grouping, user-defined functions, or schema-aware processing to remain within the 1.0 and 1.0 specifications. These constraints ensure compatibility but may require workarounds for complex transformations in modern applications.

Usage and Integration

In Microsoft Products

MSXML is pre-installed on and later versions of the operating system, with specific versions bundled depending on service packs and updates; for instance, MSXML 3.0 is included in , while MSXML 6.0 SP2 is part of SP3. In the Windows ecosystem, MSXML supports XML HTTP requests in (IIS) through components like ServerXMLHTTP, enabling server-side XML processing in ASP applications. Additionally, it is utilized in the (WSH) for scripting tasks involving XML, such as loading and manipulating DOM documents in or files. Within the suite, MSXML powers XML-related features in applications like Word and Excel from the 2003 to 2007 releases, particularly MSXML 5.0, which facilitates tasks such as XML data and document manipulation. For example, it supports the processing of XML schemas and transformations in 2007's Open XML format handling. In later versions, MSXML components remain present for legacy compatibility, though newer XML functionalities increasingly rely on updated or alternative parsers. MSXML integrates with other products, including SQL Server starting from version 2000, where it underpins XML query capabilities through the SQLXML component for generating and parsing XML data from relational queries. In from versions 5 to 11, MSXML enables client-side XML processing, including DOM manipulation and transformations for dynamic web content. MSXML is distributed through various Microsoft components, such as Microsoft Data Access Components (MDAC), the .NET Framework, and security updates that install or update specific versions like MSXML 6.0. Version selection occurs via registry entries, where applications specify ProgIDs (e.g., MSXML2.DOMDocument.6.0) to invoke a particular MSXML version from the system's registered components.

In Application Development

Developers commonly integrate MSXML into applications through scripting languages such as and , where objects are instantiated using the CreateObject function or ActiveXObject constructor with version-specific ProgIDs. For example, in , a DOMDocument object can be created as Set xmlDoc = CreateObject("Msxml2.DOMDocument.6.0"), enabling XML parsing and manipulation within scripts. This approach is prevalent in legacy web environments like (ASP) and HTML Applications (HTA), where MSXML facilitates server-side or client-side XML handling without requiring compiled code. In native code environments, such as C++ or Visual Basic 6 (VB6), MSXML components are accessed via COM interfaces, typically using the #import directive in C++ to generate smart pointers from type libraries or CoCreateInstance for direct instantiation with CLSIDs like CLSID_DOMDocument60. Error handling involves checking HRESULT return values from these calls to manage failures, such as invalid ProgIDs or missing DLLs like msxml6.dll. For instance, in C++, developers include headers like msxml6.h and link against msxml6.lib to ensure proper COM initialization and object creation. Best practices emphasize using version-specific ProgIDs, such as "Msxml2.DOMDocument.6.0", to target particular MSXML installations and avoid conflicts from side-by-side deployments, as version-independent ProgIDs were deprecated after MSXML 3.0 to promote stability. For asynchronous operations, the IXMLHttpRequest interface (accessible via ProgIDs like "Msxml2.XMLHTTP.6.0") supports non-blocking HTTP requests by setting the async parameter to true in the open method, serving as a foundational for early AJAX implementations in web applications. Developers must implement event handlers, such as onreadystatechange, to process responses upon completion. For modern application development, Microsoft recommends alternatives to MSXML, including XmlLite for lightweight, forward-only XML parsing in native C++ scenarios requiring high performance and low memory usage, as it avoids the overhead of full DOM loading. In managed environments, .NET Framework classes like XmlDocument, XmlReader, and to XML provide integrated, W3C-compliant XML handling without COM dependencies, facilitating easier migration from MSXML by rewriting instantiation and manipulation code to use managed APIs. Upgrading legacy MSXML-dependent projects to these options enhances security and compatibility with contemporary platforms.

Security Considerations

Known Vulnerabilities

MSXML, particularly versions 3.0 and earlier, has been susceptible to XML external entity (XXE) attacks that enable server-side request forgery (SSRF) and denial-of-service (DoS) conditions such as the "billion laughs" or exponential entity expansion attack. Version 6.0 mitigates many such risks by disabling DTDs and external entity resolution by default, though specific vulnerabilities have been addressed in updates. In these vulnerabilities, malicious XML documents with nested external or internal entities can cause the parser to expand content exponentially, consuming excessive memory and CPU resources, potentially leading to system crashes or resource exhaustion. For instance, a small input XML file under 1 KB can expand to over 3 GB in memory through repeated entity references like &lol9; resolving to billions of strings. These issues were documented in Microsoft's analysis of XML DoS attacks and addressed in security updates like MS14-033, which fixed an information disclosure vulnerability via improper handling of external entity URIs in MSXML 3.0 and 6.0, preventing unauthorized access to local or remote resources. Buffer overflow vulnerabilities in MSXML's XSLT processing have allowed remote code execution by exploiting malformed stylesheets. A notable example is the in the XSLT engine (CVE-2006-4686), where specially crafted XSL content could overflow buffers during transformation, enabling in the context of the user viewing a malicious web page via . This affected MSXML versions 3.0, 4.0, and 6.0, with exploitation possible through web-based attacks requiring no user privileges beyond browsing. Microsoft resolved this in security bulletin MS06-061 via updates that strengthened input validation in the processor. Denial-of-service vulnerabilities related to schema parsing and validation in MSXML have permitted resource exhaustion through malformed XML schemas or documents. For example, improper handling of HTTP responses in the Msxml2.XMLHTTP.3.0 component (CVE-2010-2561) could lead to DoS or code execution when receiving specially crafted HTTP responses, affecting MSXML 3.0 on various Windows platforms. These flaws were exploitable via crafted web content and remained a risk in unpatched obsolete versions. Microsoft patched this in bulletin MS10-051, enhancing response validation to prevent crashes or hangs during parsing. Additionally, broader XML entity expansion issues, including those impacting schema validation contexts, contribute to DoS risks in older parsers. Later vulnerabilities include remote code execution issues in MSXML's parsing and XSLT components. For instance, CVE-2014-4118 (MS14-067) allowed RCE when MSXML improperly handled XSLT template caching, affecting versions 3.0 and 6.0 across multiple Windows platforms. Similarly, CVE-2016-0147 (MS16-040) enabled RCE in MSXML 3.0 via crafted XML input, and CVE-2018-8420 permitted RCE when the MSXML parser processed untrusted input. These were fixed in respective security updates. Components such as IXMLHttpRequest and the schema validation engine in MSXML are commonly targeted, with exploits often delivered via malformed XML over HTTP protocols in web applications or browsers. These vulnerabilities typically require user interaction, like loading a malicious , but can lead to remote code execution or DoS without . Most known vulnerabilities have been addressed through service packs, cumulative updates, and Windows patches beyond MSXML 6.0 SP3, which incorporates early fixes for issues including handling and buffer management. As of November 2025, supported versions of MSXML continue to receive updates via , though obsolete installations like unpatched MSXML 3.0 on end-of-life operating systems remain vulnerable. Users are advised to apply these updates to mitigate risks in legacy deployments.

Best Practices

To enhance when using MSXML, developers should disable DTD by setting the resolveExternals to false on DOMDocument objects, which prevents the parser from resolving external such as DTDs or schemas and mitigates risks like XML external entity (XXE) attacks; this is the default in MSXML 6.0 but must be explicitly set in earlier versions like MSXML 3.0. Additionally, set validateOnParse to false to avoid automatic validation against DTDs or schemas during , further reducing exposure to malicious inputs without external dependencies. For network operations with XMLHTTP, always use to encrypt data transmission and prevent interception of sensitive XML content. Input validation is essential: limit character lengths (e.g., avoid exceeding 32 KB for loadXML) and sanitize against invalid ranges to prevent buffer overflows or silent failures. For optimal performance, leverage the schema cache in MSXML by adding schemas via the schemas collection on DOMDocument objects, which stores XML Schema definitions by target namespace to avoid repeated loading and validation, improving efficiency for repeated document processing; MSXML 6.0 enhances this with separate storage for imported schemas and atomic addition operations. Similarly, cache XSLT stylesheets using the XSLTemplate object to compile transformations once and reuse them, reducing overhead in multi-document scenarios.) For large XML documents, prefer the SAX (Simple API for XML) parser over DOM, as it processes data event-based without building an in-memory tree, requiring significantly less memory and enabling linear streaming.) Enable asynchronous loading by default (via the async property set to true on DOMDocument), which allows non-blocking parsing and improves responsiveness in applications handling sizable files. To ensure compatibility across environments, always specify the MSXML version in ProgIDs, such as Msxml2.DOMDocument.6.0 instead of version-independent ones like MSXML2.DOMDocument, to bind to a precise implementation and avoid unintended fallbacks to older versions.) Test applications with side-by-side installations of multiple MSXML versions, as supported since MSXML 4.0 on and later, to verify behavior when different components coexist without conflicts.) Given the of MSXML 4.0 and 5.0, conduct audits of codebases to identify usage of these versions (e.g., via ProgID searches or dependency scans), as they no longer receive updates and pose risks on modern systems. For new development or migrations, transition to lighter alternatives like XmlLite for native C++ applications requiring a fast, non-validating forward-only parser that outperforms MSXML in memory and speed for pull-based processing, or use .NET's XmlReader class for managed code, which provides efficient streaming without full DOM loading. For testing and maintenance, employ tools like Altova XMLSpy to validate XML compliance against schemas and simulate MSXML parsing behaviors, ensuring documents adhere to standards before deployment. Regularly monitor systems for unpatched MSXML installations using Windows Update or security scanners to confirm versions like MSXML 6.0 are applied, as older unmaintained components remain vulnerable.

References

  1. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms760399%28v=vs.85%29
  2. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms763742%28v=vs.85%29
  3. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/jj152146%28v=vs.85%29
  4. https://learn.microsoft.com/en-us/answers/questions/3891969/latest-msxml-version
  5. https://learn.microsoft.com/en-us/answers/questions/2541408/what-is-microsoft-xml-core-services
  6. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms753804%28v=vs.85%29
  7. https://learn.microsoft.com/en-us/office/client-developer/infopath/form-templates/working-with-msxml-and-system-xml-using-the-infopath-2003-object-model
  8. https://www.oit.va.gov/Services/TRM/ToolPage.aspx?tid=6056
  9. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms756987%28v=vs.85%29
  10. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms762799%28v=vs.85%29
  11. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms766508%28v=vs.85%29
  12. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms752837%28v=vs.85%29
  13. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms759148%28v=vs.85%29
  14. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms764622%28v=vs.85%29
  15. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms762757%28v=vs.85%29
  16. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms753751%28v=vs.85%29
  17. https://www.xml.com/pub/a/w3j/s3.paoli.html
  18. https://learn.microsoft.com/en-us/previous-versions/troubleshoot/msxml/list-of-xml-parser-versions
  19. https://betawiki.net/wiki/Internet_Explorer_4
  20. https://learn.microsoft.com/en-us/archive/msdn-magazine/2001/december/xml-files-what-s-new-in-msxml-4-0
  21. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/jj152146(v=vs.85)
  22. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms760399(v=vs.85)
  23. https://learn.microsoft.com/en-us/archive/msdn-magazine/2002/february/web-q-a-threading-in-msxml-sorting-xml-order-by-changing-mouse-pointer-and-more
  24. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms762314(v=vs.85)
  25. https://learn.microsoft.com/en-us/openspecs/ie_standards/ms-xmlns/06273fe0-d3b1-40b4-916e-54074525ee35
  26. https://learn.microsoft.com/en-us/archive/msdn-magazine/2000/november/the-xml-files-sax-the-simple-api-for-xml
  27. https://learn.microsoft.com/en-us/openspecs/ie_standards/ms-dom2cx/d9893f5e-618a-4774-bf69-d576267235a8
  28. https://learn.microsoft.com/en-us/archive/msdn-magazine/2000/september/the-xml-files-msxml-3-0-supports-xpath-1-0-xslt-1-0-xdr-and-sax2
  29. https://www.tmurgent.com/appv/en/88-tools/app-v-4-tools/157-msxml-versions-chart
  30. https://mskb.pkisolutions.com/kb/973686
  31. https://download.cnet.com/microsoft-core-xml-services-msxml-6-0/3000-7241_4-10725999.html
  32. https://support.microsoft.com/en-us/topic/description-of-an-update-for-msxml-core-services-6-0-service-pack-2-9b310b5a-3a90-ebc3-e1bd-97b42266b1ef
  33. https://learn.microsoft.com/en-us/lifecycle/products/microsoft-xml-core-services-40
  34. https://learn.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-002
  35. https://learn.microsoft.com/en-us/security-updates/securitybulletins/2002/ms02-008
  36. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms756987(v=vs.85)
  37. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms756003(v=vs.85)
  38. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms765513(v=vs.85)
  39. https://learn.microsoft.com/en-us/openspecs/ie_standards/ms-xpath/37986bf3-9399-491e-8c9c-bcb86c3ec435
  40. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms757846%28v=vs.85%29
  41. https://learn.microsoft.com/en-us/archive/msdn-magazine/2000/may/the-xml-files-xpath-xslt-and-other-xml-specifications
  42. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms764682%28v=vs.85%29
  43. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms761399%28v=vs.85%29
  44. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms763679%28v=vs.85%29
  45. https://learn.microsoft.com/en-us/previous-versions/dotnet/netframework-4.0/ms256197%28v=vs.100%29
  46. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms757858%28v=vs.85%29
  47. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/cc507436%28v=vs.85%29
  48. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms761352%28v=vs.85%29
  49. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/wlbsprov/scripting-example
  50. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms763701%28v=vs.85%29
  51. https://documentation.help/MSXML-5.0-SDK/documentation.pdf
  52. https://support.microsoft.com/en-us/topic/ms13-002-description-of-the-security-update-for-xml-core-services-5-0-january-8-2013-a8879aed-8faf-95cc-1008-1a55c86b67cc
  53. https://www.oreilly.com/library/view/gurus-guide-to/0201700476/0201700476_ch18lev1sec2.html
  54. https://learn.microsoft.com/en-us/archive/msdn-magazine/2002/may/sqlxml-3-0-build-data-driven-web-services-with-updated-xml-support-for-sql-server-2000
  55. https://learn.microsoft.com/en-us/openspecs/ie_standards/ms-xml/6237a4fd-0bd8-4451-952c-8b1b3f03bbe5
  56. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms760232%28v=vs.85%29
  57. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/cc507432%28v=vs.85%29
  58. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms757076%28v=vs.85%29
  59. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms757837%28v=vs.85%29
  60. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms757849%28v=vs.85%29
  61. https://learn.microsoft.com/en-us/previous-versions/troubleshoot/msxml/serverxmlhttp-xmlhttp-ashnc-mode
  62. https://learn.microsoft.com/en-us/dotnet/standard/data/xml/xml-processing-options
  63. https://learn.microsoft.com/en-us/archive/msdn-magazine/2009/november/xml-denial-of-service-attacks-and-defenses
  64. https://learn.microsoft.com/en-us/security-updates/securitybulletins/2014/ms14-033
  65. https://www.kb.cert.org/vuls/id/562788
  66. https://learn.microsoft.com/en-us/security-updates/securitybulletins/2006/ms06-061
  67. https://nvd.nist.gov/vuln/detail/CVE-2010-2561
  68. https://learn.microsoft.com/en-us/security-updates/securitybulletins/2010/ms10-051
  69. https://learn.microsoft.com/en-us/security-updates/securitybulletins/2014/ms14-067
  70. https://learn.microsoft.com/en-us/security-updates/securitybulletins/2016/ms16-040
  71. https://nvd.nist.gov/vuln/detail/CVE-2018-8420
  72. https://www.microsoft.com/en-us/download/details.aspx?id=43199
  73. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms759188(v=vs.85)
  74. https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ms764692(v=vs.85)
  75. https://documentation.help/MSXML-5.0-SDK/dom_howdoi_78ks.htm
  76. https://learn.microsoft.com/en-us/answers/questions/4005573/microsoft-xml-parser-%28msxml%29-and-xml-core-services
  77. https://learn.microsoft.com/en-us/archive/msdn-magazine/2007/april/xmllite-a-small-and-fast-xml-parser-for-native-c
  78. https://www.altova.com/xmlspy-xml-editor
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