CVE-2026-74979CWE-284broken-access-control

CVE-2026-74979

Critical · published August 18, 2026

CVSS v3.1

9.8

EPSS

Percentile

43.7

In the wild

Unconfirmed

What it is

Mitigation bypass in the Add-ons Manager component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.

The record

Technical detail

CVSS v3.1: 9.8 · CRITICAL
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0: Not supplied
EPSS: 0.00525 · 43.7th percentile
Weakness: CWE-284 · Improper Access Control
Published: 2026-08-18T17:17Z

Affected products (4)

Product	Versions	Fixed in
mozilla/firefox	< 153.1.0	153.1.0
mozilla/firefox	< 154.0.0	154.0.0
mozilla/thunderbird	< 153.1.0	153.1.0
mozilla/thunderbird	< 154.0	154.0

References (5)

https://bugzilla.mozilla.org/show_bug.cgi?id=2045676 · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-74/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-77/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-78/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-80/ · [email protected]

EPSS history

Timeline

18 AUG 12:23Z
Mitigation bypass in the Add-ons Manager component
cvelistv5