CVE-2025-5269 Affecting firefox-esr package, versions <128.11-r0


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.41% (34th percentile)

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  • Snyk IDSNYK-CHAINGUARDLATEST-FIREFOXESR-17764102
  • published1 Jul 2026
  • disclosed27 May 2025

Introduced: 27 May 2025

CVE-2025-5269  (opens in a new tab)

How to fix?

Upgrade Chainguard firefox-esr to version 128.11-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream firefox-esr package and not the firefox-esr package as distributed by Chainguard. See How to fix? for Chainguard relevant fixed versions and status.

Memory safety bug present in Firefox ESR 128.10, and Thunderbird 128.10. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox ESR 128.11 and Thunderbird 128.11.

CVSS Base Scores

version 3.1