CVE-2026-74956CWE-843

CVE-2026-74956

Critical · published August 18, 2026

CVSS v3.1
9.1
EPSS
0%
Percentile
41.8
In the wild
Unconfirmed
What it is

Same-origin policy bypass in the DOM: Service Workers 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
9.1 · 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
0.00498 · 41.8th percentile
Weakness
CWE-843 · Access of Resource Using Incompatible Type ('Type Confusion')
Published
2026-08-18T17:17Z
Affected products (4)
ProductVersionsFixed in
mozilla/firefox< 153.1.0153.1.0
mozilla/firefox< 154.0.0154.0.0
mozilla/thunderbird< 153.1.0153.1.0
mozilla/thunderbird< 154.0154.0
References (5)
https://bugzilla.mozilla.org/show_bug.cgi?id=2032406 · [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
    Same-origin policy bypass in the DOM: Service Workers component
    cvelistv5