CVE-2026-12304

CRITICAL 9.1CVE-2026-12304 · Published 16/06/2026 · updated 26/10/2026

Package	Affected versions	Patched versions
firefox mozilla	`< 140.12.0< 152.0.0`	`140.12.0152.0.0`
thunderbird mozilla	`< 140.12.0< 152.0.0`	`140.12.0152.0.0`

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.

References

bugzilla.mozilla.org/show_bug.cgi · Permissions Required
mozilla.org/security/advisories/mfsa2026-57 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-58 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-60 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-61 · Vendor Advisory

Running one of these products? Scan your site to see whether it exposes a vulnerable version.

Scan my site free