CVE-2026-74960CWE-284CWE-346broken-access-control

CVE-2026-74960

High · published August 18, 2026

CVSS v3.1
8.1
EPSS
0%
Percentile
12.3
In the wild
Unconfirmed
What it is

Site isolation issue in the WebExtensions 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
8.1 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00224 · 12.3th percentile
Weaknesses
CWE-284 · Improper Access Control; CWE-346 · Origin Validation Error
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=2049148 · [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
    Site isolation issue in the WebExtensions component
    cvelistv5