CVE-2026-74989: mozilla firefox, mozilla thunderbird

CVSS 9.8 (critical) · published 2026-08-18

Internally found bugs present in Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154 and Thunderbird 154.

Affected products (NVD): mozilla firefox, mozilla thunderbird

Fixed in (NVD): 154.0.0, 154.0

Weakness: CWE-119

Source: NVD CVE-2026-74989

References

• https://bugzilla.mozilla.org/buglist.cgi?bug_id=2022257%2C2027351%2C2027380%2C2029289
• https://bugzilla.mozilla.org/buglist.cgi?bug_id=2027388%2C2029750%2C2029794%2C2043298%2C2045126%2C2049810%2C2051741
• https://www.mozilla.org/security/advisories/mfsa2026-74/
• https://www.mozilla.org/security/advisories/mfsa2026-78/

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