CVE-2026-74956

Same-origin policy bypass in the DOM: Service Workers component

State: Published
Severity: 9.1 Critical
Published: Aug 18, 2026
Updated: Aug 18, 2026
Reserved: Aug 17, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	9.1 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N	CISA-ADP

Weaknesses

CWE-843 Access of Resource Using Incompatible Type ('Type Confusion')

Affected Products

Product	Versions
FirefoxMozilla	153.1 through 153.*Not affected 154 and laterNot affected
ThunderbirdMozilla	153.1 through 153.*Not affected 154 and laterNot affected

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2032406
https://www.mozilla.org/security/advisories/mfsa2026-74/
https://www.mozilla.org/security/advisories/mfsa2026-77/
https://www.mozilla.org/security/advisories/mfsa2026-78/
https://www.mozilla.org/security/advisories/mfsa2026-80/

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