Stack-Based Buffer Overflow in libxml2

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Summary

CVECVE-2026-11979
StatePUBLISHED
AssignerCERT-PL
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-29 14:16:40 UTC
Updated2026-06-30 20:22:07 UTC
Descriptionlibxml2 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.

Risk And Classification

Primary CVSS: v4.0 1.8 LOW from [email protected]

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:X/V:X/RE:X/U:X

EPSS: 0.001480000 probability, percentile 0.044090000 (date 2026-07-04)

Problem Types: CWE-121 | CWE-121 CWE-121: Stack-based Buffer Overflow

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary1.8LOWCVSS: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/C...
4.0CNACVSS1.8LOWCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:L/SC:L/SI:L/SA:N
3.1[email protected]Primary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS v4.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
Active
Confidentiality
None
Integrity
None
Availability
Low
Sub Conf.
Low
Sub Integrity
Low
Sub Availability
None

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:X/V:X/RE:X/U:X

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Xmlsoft Libxml2 All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Xmlsoft Libxml2 affected 2.15.3 custom Not specified

References

ReferenceSourceLinkTags
gitlab.gnome.org/GNOME/libxml2/-/commit/c2e233fc1b341685fc99621b2768b503f777a72e [email protected] gitlab.gnome.org Patch
cert.pl/en/posts/2026/06/CVE-2026-11979 [email protected] cert.pl Third Party Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Michał Majchrowicz (AFINE Team) (en)

CNA: Marcin Wyczechowski (AFINE Team) (en)

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