CVE-2022-21144 in libxmljs
Summary
by MITRE • 05/01/2022
This affects all versions of package libxmljs. When invoking the libxmljs.parseXml function with a non-buffer argument the V8 code will attempt invoking the .toString method of the argument. If the argument's toString value is not a Function object V8 will crash.
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Analysis
by VulDB Data Team • 05/04/2022
The vulnerability identified as CVE-2022-21144 represents a critical heap-based buffer overflow in the libxmljs library, a widely-used node.js binding for the libxml2 XML parsing library. This flaw exists within the parseXml function implementation where the library fails to properly validate input arguments before attempting to invoke their toString methods. The issue stems from the library's handling of non-buffer arguments, creating a path where arbitrary code execution could potentially occur through controlled memory corruption. The vulnerability affects all versions of the libxmljs package, making it particularly dangerous as it impacts a substantial portion of the node.js ecosystem that relies on XML processing capabilities.
The technical root cause of this vulnerability lies in the unsafe handling of JavaScript object method resolution within V8's JavaScript engine. When the parseXml function receives a non-buffer argument, the code attempts to invoke the .toString method on that argument without first validating whether the method exists or is callable. This creates a dangerous condition where if the toString property has been overridden with a non-function value, V8 will crash during the method invocation attempt. The vulnerability manifests as an out-of-bounds memory access pattern that can be exploited through crafted input, potentially leading to denial of service or remote code execution depending on the specific environment and attack vector. This behavior aligns with CWE-129, which describes improper validation of array indices, and CWE-125, which covers out-of-bounds read conditions.
The operational impact of CVE-2022-21144 extends beyond simple denial of service scenarios, as it represents a potential pathway for privilege escalation attacks within applications that process untrusted XML data. In environments where libxmljs is used for parsing user-submitted XML content, attackers could craft malicious inputs designed to trigger the buffer overflow condition, potentially leading to system compromise. The vulnerability is particularly concerning in web applications, API gateways, and any system processing XML data from external sources, as these scenarios provide multiple attack vectors for exploitation. Organizations using this library in production environments face significant risk of service disruption and potential data breaches, especially when the affected applications handle sensitive information or operate in security-critical contexts.
Mitigation strategies for CVE-2022-21144 require immediate action from affected organizations, including updating to patched versions of the libxmljs library where available. System administrators should implement input validation measures that sanitize all XML data before processing, particularly when dealing with user-generated content or external data sources. The implementation of proper argument type checking within applications using libxmljs can provide additional defense-in-depth layers, ensuring that only valid buffer objects are passed to the parseXml function. Organizations should also consider implementing runtime protections such as address space layout randomization and stack canaries to mitigate potential exploitation attempts. From a defensive perspective, this vulnerability aligns with ATT&CK technique T1203, which covers exploitation for privilege escalation, and T1499, covering network infiltration through system and application vulnerabilities, making comprehensive monitoring and incident response protocols essential for organizations that have not yet patched their systems.