CVE-2026-2776 Affecting firefox-esr package, versions <140.8.0esr-1


Severity

Recommended
0.0
critical
0
10

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Threat Intelligence

EPSS
0.03% (9th percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-FIREFOXESR-15339349
  • published25 Feb 2026
  • disclosed24 Feb 2026

Introduced: 24 Feb 2026

CVE-2026-2776  (opens in a new tab)

How to fix?

Upgrade Debian:unstable firefox-esr to version 140.8.0esr-1 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 Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. 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