CVE-2026-2778 Affecting firefox-esr package, versions <140.8.0-r0


Severity

Recommended
0.0
critical
0
10

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Threat Intelligence

EPSS
0.48% (38th percentile)

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  • Snyk IDSNYK-CHAINGUARDLATEST-FIREFOXESR-17765295
  • published1 Jul 2026
  • disclosed24 Feb 2026

Introduced: 24 Feb 2026

CVE-2026-2778  (opens in a new tab)

How to fix?

Upgrade Chainguard firefox-esr to version 140.8.0-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.

Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

CVSS Base Scores

version 3.1