CVE-2013-1969 in libxml2
Summary
by MITRE
Multiple use-after-free vulnerabilities in libxml2 2.9.0 and possibly other versions might allow context-dependent attackers to cause a denial of service (crash) and possibly execute arbitrary code via vectors related to the (1) htmlParseChunk and (2) xmldecl_done functions, as demonstrated by a buffer overflow in the xmlBufGetInputBase function.
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Analysis
by VulDB Data Team • 12/27/2024
The vulnerability identified as CVE-2013-1969 represents a critical security flaw in the libxml2 library version 2.9.0 and potentially earlier releases. This issue manifests as multiple use-after-free vulnerabilities that create exploitable conditions within the XML parsing functionality. The affected functions htmlParseChunk and xmldecl_done serve as primary attack vectors where memory management errors occur, leading to unpredictable behavior when processing malformed XML content. The vulnerability's severity is amplified by its potential to enable remote code execution in addition to denial of service conditions, making it particularly dangerous for applications that process untrusted XML data.
The technical implementation of this vulnerability stems from improper memory management practices within the libxml2 parsing engine. When the htmlParseChunk function processes XML input, it fails to properly validate memory allocation states before accessing previously freed memory locations. Similarly, the xmldecl_done function exhibits similar memory management flaws that can result in use-after-free conditions. The buffer overflow occurring in xmlBufGetInputBase function demonstrates how these memory corruption issues can cascade into more severe exploitation opportunities. These flaws are categorized under CWE-416, which specifically addresses use-after-free vulnerabilities where program code accesses memory after it has been freed, and additionally align with CWE-122, which covers heap-based buffer overflow conditions.
The operational impact of CVE-2013-1969 extends far beyond simple application crashes, as it can potentially enable remote code execution in vulnerable systems. Attackers can craft malicious XML payloads that trigger these use-after-free conditions when processed by applications relying on libxml2 for XML parsing operations. This vulnerability affects numerous software applications including web browsers, content management systems, and enterprise applications that handle XML data processing. The context-dependent nature of the attack means that exploitation requires specific conditions but can be achieved through crafted XML input that leverages the memory corruption flaws in the parsing functions. The vulnerability's exploitation can result in complete system compromise when successful, as demonstrated by similar use-after-free vulnerabilities in other XML parsers that have been weaponized in real-world attacks.
Mitigation strategies for CVE-2013-1969 should prioritize immediate patching of affected libxml2 versions to 2.9.1 or later, which contain the necessary memory management fixes. Organizations should implement input validation and sanitization measures to prevent processing of untrusted XML content, particularly in web applications. Network segmentation and application whitelisting can reduce the attack surface by limiting access to XML processing functions. The vulnerability's classification under ATT&CK technique T1203, which covers exploitation of memory corruption vulnerabilities, indicates that defensive measures should include monitoring for unusual memory access patterns and implementing exploit mitigation techniques such as address space layout randomization. Regular security assessments and vulnerability scanning should be conducted to identify systems running vulnerable libxml2 versions, while application developers should ensure proper error handling and memory management practices in their XML processing code to prevent similar issues from occurring in custom implementations.