CVE-2026-0891: Vulnerability in Mozilla Firefox
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.
AI Analysis
Technical Summary
This vulnerability consists of multiple memory safety bugs in Firefox ESR 140.6, Thunderbird ESR 140.6, Firefox 146, and Thunderbird 146. Some bugs showed evidence of memory corruption, which could allow an attacker to run arbitrary code with sufficient effort. Mozilla addressed these issues by releasing fixes in Firefox 147, Firefox ESR 140.7, Thunderbird 147, and Thunderbird ESR 140.7. The CVSS v3.1 base score is 8.1, indicating high impact on confidentiality, integrity, and availability. The vulnerability is categorized under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer).
Potential Impact
Successful exploitation could lead to arbitrary code execution due to memory corruption. The vulnerability impacts confidentiality, integrity, and availability of affected systems. There are no known exploits in the wild currently, but the potential for exploitation exists given the nature of the memory safety bugs.
Mitigation Recommendations
A fix is available and has been released by Mozilla. Users and administrators should upgrade to Firefox 147, Firefox ESR 140.7, Thunderbird 147, or Thunderbird ESR 140.7 to remediate this vulnerability. No additional mitigation actions are required beyond applying these official updates.
CVE-2026-0891: Vulnerability in Mozilla Firefox
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 v3.1
Score 8.1high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability consists of multiple memory safety bugs in Firefox ESR 140.6, Thunderbird ESR 140.6, Firefox 146, and Thunderbird 146. Some bugs showed evidence of memory corruption, which could allow an attacker to run arbitrary code with sufficient effort. Mozilla addressed these issues by releasing fixes in Firefox 147, Firefox ESR 140.7, Thunderbird 147, and Thunderbird ESR 140.7. The CVSS v3.1 base score is 8.1, indicating high impact on confidentiality, integrity, and availability. The vulnerability is categorized under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer).
Potential Impact
Successful exploitation could lead to arbitrary code execution due to memory corruption. The vulnerability impacts confidentiality, integrity, and availability of affected systems. There are no known exploits in the wild currently, but the potential for exploitation exists given the nature of the memory safety bugs.
Mitigation Recommendations
A fix is available and has been released by Mozilla. Users and administrators should upgrade to Firefox 147, Firefox ESR 140.7, Thunderbird 147, or Thunderbird ESR 140.7 to remediate this vulnerability. No additional mitigation actions are required beyond applying these official updates.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-01-13T13:30:59.286Z
- State
- PUBLISHED
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-01/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-03/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-04/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-05/","vendor":"Mozilla"},{"url":"https://access.redhat.com/security/cve/CVE-2026-0891","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:2231","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:2271","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:2286","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:0667","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:2220","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:2074","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:1471","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:2073","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:1461","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:2070","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:1487","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:2069","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:1462","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:2047","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:1413","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:2044","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:1415","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:2041","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:1414","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:2043","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:1320","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:0694","vendor":"Red Hat"},{"url":"https://access.redhat.com/errata/RHSA-2026:0924","vendor":"Red Hat"}]
Threat ID: 69664f11a60475309f2ea335
Added to database: 01/13/2026, 13:56:33 UTC
Last enriched: 07/15/2026, 08:25:03 UTC
Last updated: 09/10/2026, 19:36:52 UTC
Views: 367
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