CVE-2026-11979: Stack-Based Buffer Overflow in libxml2
libxml2 is vulnerable to multiple stack-based buffer overflows in the xmlcatalog utility when running in --shell mode. The usershell() function processes user input using fixed-size stack buffers without proper bounds checking. By supplying an overly long input line, an attacker can overflow internal buffers (command, arg, and argv) during input parsing. This results in memory corruption within the stack frame. Successful exploitation may cause a crash or potentially allow arbitrary code execution in the context of the xmlcatalog process.
This issue has been fixed in the commit c2e233fc.
NOTE: The maintainers of this project did not agree that this issue is a vulnerability and considered it a bug.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
libxml2 (xmlcatalog utility, --shell mode)to a version that resolves this vulnerability.Patch c2e233fc
Event History
Frequently Asked Questions
What is the severity of CVE-2026-11979?
CVE-2026-11979 has a risk score of 48, indicating a significant risk due to stack-based buffer overflows.
How do I fix CVE-2026-11979?
To fix CVE-2026-11979, update the libxml2 package to the latest version that addresses the buffer overflow vulnerabilities.
What systems are affected by CVE-2026-11979?
CVE-2026-11979 affects the libxml2 xmlcatalog utility when running in --shell mode.
What type of vulnerability is CVE-2026-11979?
CVE-2026-11979 is classified as a stack-based buffer overflow vulnerability.
Can CVE-2026-11979 be exploited remotely?
Yes, CVE-2026-11979 can potentially be exploited by an attacker providing malicious input in a user shell session.