CVE-2026-74990: mozilla firefox, mozilla thunderbird

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

Internally found bugs present in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and 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, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

Affected products (NVD): mozilla firefox, mozilla thunderbird

Fixed in (NVD): 115.39.0, 140.14.0, 153.1.0

Weakness: CWE-119

Source: NVD CVE-2026-74990

References

• https://bugzilla.mozilla.org/buglist.cgi?bug_id=2045762%2C2052401%2C2058208
• https://bugzilla.mozilla.org/buglist.cgi?bug_id=2045774%2C2048490%2C2050864%2C2053159%2C2053260%2C2053261%2C2053582%2C2053599%2C2053607%2C2053608%2C2053853%2C2054626%2C2054627%2C2054635%2C2054677%2C2054740%2C2054832%2C2056792%2C2057098%2C2057100%2C2057101%2C2057103%2C2057117%2C2057118%2C2058048%2C2058049%2C2058622%2C2058623%2C2058665%2C2058666%2C2059121%2C2059164%2C2059188
• https://www.mozilla.org/security/advisories/mfsa2026-74/
• https://www.mozilla.org/security/advisories/mfsa2026-75/
• https://www.mozilla.org/security/advisories/mfsa2026-76/
• https://www.mozilla.org/security/advisories/mfsa2026-77/
• https://www.mozilla.org/security/advisories/mfsa2026-78/
• https://www.mozilla.org/security/advisories/mfsa2026-79/
• https://www.mozilla.org/security/advisories/mfsa2026-80/

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