CVE-2026-12304

Same-origin policy bypass in the Networking: Cookies component

State: Published
Severity: 9.1 Critical
Published: Jun 16, 2026
Updated: Jun 16, 2026
Reserved: Jun 15, 2026

Description

Same-origin policy bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.

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-346 Origin Validation Error

Affected Products

Product	Versions
FirefoxMozilla	140.12 through 140.*Not affected 152 and laterNot affected
ThunderbirdMozilla	140.12 through 140.*Not affected 152 and laterNot affected

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2034944
https://www.mozilla.org/security/advisories/mfsa2026-57/
https://www.mozilla.org/security/advisories/mfsa2026-58/
https://www.mozilla.org/security/advisories/mfsa2026-60/
https://www.mozilla.org/security/advisories/mfsa2026-61/

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