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Vulnerability record · CVE-2026-11979 · published 29 June 2026

CVE-2026-11979: Xmlsoft libxml2 stack-based buffer overflow vulnerability

Xmlsoft · 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.

1.8 CVSS 4.0 Low EPSS 0.15% · top 96.6% CWE-121 · Stack-based buffer overflow
1.8CVSS 4.0 base score
0.15%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
30 Jun 2026Last modified by NVD

Description

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.

CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:L/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://cert.pl/en/posts/2026/06/CVE-2026-11979 Third Party Advisory
https://gitlab.gnome.org/GNOME/libxml2/-/commit/c2e233fc1b341685fc99621b2768b503f777a72e Patch

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-11979), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.