Integer Overflow Vulnerability in libxml2: Potential Stack-Based Buffer Overflow
Summary
DEBIAN-CVE-2025-6021: A flaw was found in libxml2's xmlBuildQName function, where integer overflows in buffer size calculations can lead to a stack-based buffer overflow. Affects libxml2 versions < 2.9.10+dfsg-6.7+deb11u8. Fixed in 2.9.10+dfsg-6.7+deb11u8. How to fix ↓
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Background
libxml2 is a widely used XML parsing library that provides a range of functionalities for processing XML documents. It is known for its performance and compliance with standards. However, it is susceptible to vulnerabilities that can compromise its integrity and the applications relying on it. This specific vulnerability arises from flaws in the xmlBuildQName function, which can lead to severe consequences when handling crafted XML input.
Vulnerability Detail
A flaw was found in libxml2's xmlBuildQName function, where integer overflows in buffer size calculations can lead to a stack-based buffer overflow. This issue can result in memory corruption or a denial of service when processing crafted input. Attackers may exploit this vulnerability to execute arbitrary code or crash applications that utilize libxml2 for XML processing.
How To Fix
Minimum fixed version
2.9.10+dfsg-6.7+deb11u8
This is the first release that contains the fix.
sudo apt-get install --only-upgrade libxml2Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary measure, avoid processing untrusted XML input until the package is updated. Implement input validation to ensure that only safe and expected XML data is processed.
Conclusion
The integer overflow vulnerability in libxml2's xmlBuildQName function poses significant risks, including memory corruption and denial of service. It is crucial to update to the patched versions of the library to mitigate these risks and ensure the security of applications that rely on libxml2.
See every vulnerability recorded for libxml2 →
FAQ
libxml2 is an XML parsing library that provides tools for reading, manipulating, and writing XML documents.
If your application uses libxml2 to process XML data, it may be vulnerable to memory corruption or denial of service attacks due to this flaw.
Check your installed version of libxml2 against the patched versions provided in the 'how_to_fix' section. You can also use tools like Vulert to monitor for vulnerabilities.
Vulert is a service that monitors and alerts for open-source vulnerabilities in your software using just a manifest file like package-lock.json.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
References
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