CVE-2026-0891
Memory safety bugs fixed in Firefox ESR 140.7, Thunderbird ESR 140.7, Firefox 147 and Thunderbird 147
CVSS Score
8.1
EPSS Score
0.0%
EPSS Percentile
0th
Memory safety bugs present in Firefox ESR 140.6, Thunderbird ESR 140.6, Firefox 146 and Thunderbird 146. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 147, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.
| Vendor | mozilla |
| Product | firefox |
| Ecosystems | |
| Industries | Technology |
| Published | Jan 13, 2026 |
| Last Updated | Apr 13, 2026 |
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Affected Versions
Mozilla / Firefox
All versions affected Mozilla / Thunderbird
All versions affected References
bugzilla.mozilla.org: https://bugzilla.mozilla.org/buglist.cgi?bug_id=1964722%2C2000981%2C2003100%2C2003278 mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-01/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-03/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-04/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-05/
Credits
Andrew McCreight, Dennis Jackson and the Mozilla Fuzzing Team