CVE-2026-100804: mozilla firefox, mozilla thunderbird

CVSS 9.6 (critical) · published 2026-09-29

Sandbox escape due to use-after-free in the Preferences: Backend component. This vulnerability was fixed in Thunderbird 157 and Firefox 157.

Affected products (NVD): mozilla firefox, mozilla thunderbird

Fixed in (NVD): 157.0.0, 157.0

Weakness: CWE-416

Source: NVD CVE-2026-100804

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=2058647
• https://www.mozilla.org/security/advisories/mfsa2026-101/
• https://www.mozilla.org/security/advisories/mfsa2026-97/

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