CVE-2026-74959CWE-693

CVE-2026-74959

Critical · published August 18, 2026

CVSS v3.1
9.1
EPSS
0%
Percentile
40.3
In the wild
Unconfirmed
What it is

Mitigation bypass in the Storage: Cache API component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

The record
Technical detail
CVSS v3.1
9.1 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00479 · 40.3th percentile
Weakness
CWE-693 · Protection Mechanism Failure
Published
2026-08-18T17:17Z
Affected products (4)
ProductVersionsFixed in
mozilla/firefox< 140.14.0140.14.0
mozilla/firefox≥ 141.0, < 153.1.0153.1.0
mozilla/thunderbird< 140.14.0140.14.0
mozilla/thunderbird≥ 141.0, < 153.1.0153.1.0
References (7)
https://bugzilla.mozilla.org/show_bug.cgi?id=2047853 · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-74/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-76/ · [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/mfsa2026-79/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-80/ · [email protected]
EPSS history
Timeline
  • 18 AUG 12:23Z
    Mitigation bypass in the Storage: Cache API component
    cvelistv5