CVE-2026-2777

9.8 criticalEPSS 0.4%

Critical (9.8) in mozilla. EPSS 0.4% chance of exploitation in the next 30 days.

Privilege escalation in the Messaging System component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Severity

CVSS 3.1

9.8 critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.4% chance of exploitation in the next 30 days; higher than 38% of CVEs (scores of 2026-10-31)
CWE: CWE-269
Published: 2026-02-24
Modified: 2026-07-15
Record from: the NVD, synced 2026-10-19

Affected

mozilla:firefox
mozilla:thunderbird

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2015305
https://www.mozilla.org/security/advisories/mfsa2026-13/
https://www.mozilla.org/security/advisories/mfsa2026-14/
https://www.mozilla.org/security/advisories/mfsa2026-15/
https://www.mozilla.org/security/advisories/mfsa2026-16/

Check your stack JSON