CVE-2026-0891
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.48%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 8.1 HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.48% probability · 40th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-119
- Affected
- mozilla/firefox · mozilla/thunderbird
- Source
- security@mozilla.org
References
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=1964722%2C2000981%2C2003100%2C2003278Broken Link
- https://www.mozilla.org/security/advisories/mfsa2026-01/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-03/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-04/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-05/Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:0667
- https://access.redhat.com/errata/RHSA-2026:0694
- https://access.redhat.com/errata/RHSA-2026:0924
- https://access.redhat.com/errata/RHSA-2026:1320
- https://access.redhat.com/errata/RHSA-2026:1413
- https://access.redhat.com/errata/RHSA-2026:1414
- https://access.redhat.com/errata/RHSA-2026:1415
- https://access.redhat.com/errata/RHSA-2026:1461
- https://access.redhat.com/errata/RHSA-2026:1462
- https://access.redhat.com/errata/RHSA-2026:1471
- https://access.redhat.com/errata/RHSA-2026:1487
- https://access.redhat.com/errata/RHSA-2026:2041
- https://access.redhat.com/errata/RHSA-2026:2043
- https://access.redhat.com/errata/RHSA-2026:2044
- https://access.redhat.com/errata/RHSA-2026:2047
- https://access.redhat.com/errata/RHSA-2026:2069
- https://access.redhat.com/errata/RHSA-2026:2070
- https://access.redhat.com/errata/RHSA-2026:2073
- https://access.redhat.com/errata/RHSA-2026:2074
- https://access.redhat.com/errata/RHSA-2026:2220
- https://access.redhat.com/errata/RHSA-2026:2231
- https://access.redhat.com/errata/RHSA-2026:2271
- https://access.redhat.com/errata/RHSA-2026:2286
- https://access.redhat.com/security/cve/CVE-2026-0891
- https://bugzilla.redhat.com/show_bug.cgi?id=2428963
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.