CVE-2006-4686 in XML Core Services
Summary
by MITRE
Buffer overflow in the Extensible Stylesheet Language Transformations (XSLT) processing in Microsoft XML Parser 2.6 and XML Core Services 3.0 through 6.0 allows remote attackers to execute arbitrary code via a crafted Web page.
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Analysis
by VulDB Data Team • 04/24/2026
The vulnerability described in CVE-2006-4686 represents a critical buffer overflow flaw within Microsoft's XML parsing infrastructure that specifically affects XSLT processing capabilities. This issue impacts multiple versions of Microsoft XML Core Services including versions 3.0 through 6.0, with the vulnerability originating from the XML Parser 2.6 component. The flaw manifests when the system processes specially crafted XSLT transformations that exceed the allocated buffer space, creating potential entry points for malicious code execution. The vulnerability's severity stems from its ability to be exploited remotely through web-based attacks, making it particularly dangerous in networked environments where users may inadvertently access compromised web content.
The technical mechanism behind this buffer overflow involves improper input validation within the XSLT transformation engine of Microsoft's XML processing framework. When a maliciously crafted web page containing oversized or malformed XSLT elements is processed by the vulnerable XML parser, the system fails to properly bounds-check memory allocations during transformation operations. This lack of proper memory management allows attackers to overwrite adjacent memory locations with malicious payload data, potentially leading to arbitrary code execution with the privileges of the compromised process. The vulnerability specifically targets the memory handling routines used in XSLT processing, where the parser does not adequately validate the size or structure of incoming transformation data before attempting to process it.
From an operational perspective, this vulnerability creates significant risk for organizations relying on Microsoft XML processing capabilities for web applications, content management systems, or data transformation services. Attackers can exploit this flaw by hosting malicious web pages that contain crafted XSLT content, which when loaded in a vulnerable browser or application environment triggers the buffer overflow condition. The remote execution capability means that successful exploitation can occur without requiring local system access or user interaction beyond visiting a malicious website. This makes the vulnerability particularly dangerous in enterprise environments where users may access untrusted web content or where web applications process user-supplied XML data without proper validation.
Organizations should implement immediate mitigations including applying Microsoft's security patches and updates specifically addressing this vulnerability in XML Core Services. System administrators should also consider implementing network-level protections such as web application firewalls and content filtering solutions that can detect and block malicious XSLT content. Additionally, application developers should validate all XML input data and implement proper bounds checking in their applications that process XSLT transformations. The vulnerability aligns with CWE-121, which describes buffer overflow conditions, and represents a typical attack vector categorized under the ATT&CK framework as T1203 - Exploitation for Client Execution, emphasizing the remote code execution capabilities that make this vulnerability particularly dangerous in web-based attack scenarios.