Out-of-bounds Write Affecting firefox-esr package, versions <140.9.1-r0


Severity

Recommended
0.0
critical
0
10

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Threat Intelligence

EPSS
0.33% (25th percentile)

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  • Snyk IDSNYK-CHAINGUARDLATEST-FIREFOXESR-17765241
  • published1 Jul 2026
  • disclosed7 Apr 2026

Introduced: 7 Apr 2026

CVE-2026-5734  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

Upgrade Chainguard firefox-esr to version 140.9.1-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 bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149.0.2, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.

CVSS Base Scores

version 3.1