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.
Fix
Patch, vendor advisory and mitigation references on NVD 2
- https://www.mozilla.org/security/advisories/mfsa2026-74/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-78/ Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 5
- CwesCWE-119NVD modified 2026-10-28 17:18
- Cpes+2 CPE criteria (now 2)NVD modified 2026-10-28 17:18
- StatusPublished → ModifiedNVD modified 2026-10-28 17:18
- CVSS9.8 (v3.1, CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)NVD modified 2026-10-28 17:18
- First seenunscored · mozillaNVD modified 2026-10-28 16:36
Affected (CPE criteria) 2
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
References 4
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=2022257%2C2027351%2C2027380%2C2029289 Not Applicable
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=2027388%2C2029750%2C2029794%2C2043298%2C2045126%2C2049810%2C2051741 Not Applicable
- https://www.mozilla.org/security/advisories/mfsa2026-74/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-78/ Vendor Advisory