CVE-2026-0891

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2026-0891
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.

8.1 /10

CVSS v3 : HIGH

V3 Legend

Vector :

Exploitability : 2.2 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References
Link Resource
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1964722%2C2000981%2C2003100%2C2003278 Broken 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
Configurations

Configuration 1 (hide)

OR cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*
History

13 Apr 2026, 15:17

Type Values Removed Values Added
Summary
  • (es) Errores de seguridad de memoria presentes en Firefox ESR 140.6, Thunderbird ESR 140.6, Firefox 146 y Thunderbird 146. Algunos de estos errores mostraron evidencia de corrupción de memoria y presumimos que con suficiente esfuerzo algunos de estos podrían haber sido explotados para ejecutar código arbitrario. Esta vulnerabilidad afecta a Firefox < 147, Firefox ESR < 140.7, Thunderbird < 147 y Thunderbird < 140.7.
Summary (en) 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 affects Firefox < 147, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7. (en) 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.

22 Jan 2026, 19:13

Type Values Removed Values Added
First Time Mozilla
Mozilla firefox
Mozilla thunderbird
CPE cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
References () https://bugzilla.mozilla.org/buglist.cgi?bug_id=1964722%2C2000981%2C2003100%2C2003278 - () https://bugzilla.mozilla.org/buglist.cgi?bug_id=1964722%2C2000981%2C2003100%2C2003278 - Broken Link
References () https://www.mozilla.org/security/advisories/mfsa2026-01/ - () https://www.mozilla.org/security/advisories/mfsa2026-01/ - Vendor Advisory
References () https://www.mozilla.org/security/advisories/mfsa2026-03/ - () https://www.mozilla.org/security/advisories/mfsa2026-03/ - Vendor Advisory
References () https://www.mozilla.org/security/advisories/mfsa2026-04/ - () https://www.mozilla.org/security/advisories/mfsa2026-04/ - Vendor Advisory
References () https://www.mozilla.org/security/advisories/mfsa2026-05/ - () https://www.mozilla.org/security/advisories/mfsa2026-05/ - Vendor Advisory

15 Jan 2026, 10:16

Type Values Removed Values Added
Summary (en) 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 affects Firefox < 147 and Firefox ESR < 140.7. (en) 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 affects Firefox < 147, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7.
References
  • () https://www.mozilla.org/security/advisories/mfsa2026-04/ -
  • () https://www.mozilla.org/security/advisories/mfsa2026-05/ -

13 Jan 2026, 15:16

Type Values Removed Values Added
CVSS v2 : unknown
v3 : unknown 		v2 : unknown
v3 : 8.1
CWE CWE-119

13 Jan 2026, 14:16

Type Values Removed Values Added
New CVE
Information

Published : 2026-01-13 14:16

Updated : 2026-04-13 15:17

NVD link : CVE-2026-0891

Mitre link : CVE-2026-0891

CVE.ORG link : CVE-2026-0891

JSON object : View

Products Affected

mozilla

  • firefox
  • thunderbird
CWE
CWE-119

Improper Restriction of Operations within the Bounds of a Memory Buffer