CVE-2026-6771

CRITICAL 9.8CVE-2026-6771 · Published 21/04/2026 · updated 26/10/2026

Package	Affected versions	Patched versions
firefox mozilla	`≥ 140.0, < 140.10.0< 150.0`	`140.10.0150.0`
thunderbird mozilla	`≥ 140.0, < 140.10.0`	`140.10.0`

Description

Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

References

bugzilla.mozilla.org/show_bug.cgi · Permissions Required
mozilla.org/security/advisories/mfsa2026-30 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-32 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-33 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-34 · Vendor Advisory

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