CVE-2026-100794: mozilla firefox, mozilla thunderbird

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

Sandbox escape due to incorrect boundary conditions in the Internationalization component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

Affected products (NVD): mozilla firefox, mozilla thunderbird

Fixed in (NVD): 140.17.0, 153.4.0, 157.0.0, 157.0

Weakness: CWE-119

Source: NVD CVE-2026-100794

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=2028871
• https://www.mozilla.org/security/advisories/mfsa2026-100/
• https://www.mozilla.org/security/advisories/mfsa2026-101/
• https://www.mozilla.org/security/advisories/mfsa2026-102/
• https://www.mozilla.org/security/advisories/mfsa2026-103/
• https://www.mozilla.org/security/advisories/mfsa2026-97/
• https://www.mozilla.org/security/advisories/mfsa2026-99/

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