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 | Jul 15, 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/ access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-0891 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2428963 security.access.redhat.com: https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-0891.json access.redhat.com: https://access.redhat.com/errata/RHSA-2026:2231 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:2271 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:2286 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:0667 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:2220 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:2074 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:1471 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:2073 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:1461 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:2070 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:1487 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:2069 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:1462 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:2047 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:1413 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:2044 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:1415 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:2041 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:1414 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:2043 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:1320 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:0694 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:0924
Credits
Andrew McCreight, Dennis Jackson and the Mozilla Fuzzing Team