by Kastro
Paper/Archive/CVE-2026-12304

CVE-2026-12304

Mozilla Firefox — Same-origin policy bypass in the Networking: Cookies component

EPSS 0.2%CVSS 9.1
critical.is priorityof 100
29
CVSS 9.1 (ADP)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 8.6.086 × 201.7No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
Firefoxsee advisory140.12CNA
Thunderbirdsee advisory140.12CNA

Scores by source

CISA ADP9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CISA ADPSSVCExploitation: none · Automatable: no · Technical impact: total

References

refbugzilla.mozilla.org/show_bug.cgi?id=2034944refmozilla.org/security/advisories/mfsa2026-57refmozilla.org/security/advisories/mfsa2026-58refmozilla.org/security/advisories/mfsa2026-60refmozilla.org/security/advisories/mfsa2026-61