Use After Free Affecting expat package, versions <2.8.4-r0


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.11% (2nd percentile)

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  • Snyk IDSNYK-ALPINE321-EXPAT-19477254
  • published1 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 Alpine:3.21 expat to version 2.8.4-r0 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 Alpine. See How to fix? for Alpine:3.21 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