Use After Free Affecting expat package, versions <2.4.7-1ubuntu0.9


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.11% (2nd percentile)

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  • Snyk IDSNYK-UBUNTU2204-EXPAT-19169869
  • published5 Sept 2026
  • disclosed20 Aug 2026

Introduced: 20 Aug 2026

CVE-2026-76957  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade Ubuntu:22.04 expat to version 2.4.7-1ubuntu0.9 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream expat package and not the expat package as distributed by Ubuntu. See How to fix? for Ubuntu:22.04 relevant fixed versions and status.

libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.

CVSS Base Scores

version 3.1