CVE-2026-12304

Same-origin policy bypass in the Networking: Cookies component

CVSS 9.1 CRITICALEPSS 0.2%CWE-346

Vexday Risk Score

28Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 9.1EPSS 0.2%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

16 Jun 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

Mozilla · Firefox Mozilla · Thunderbird

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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/