CVE-2026-4720

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2026-4720
Memory safety bugs present in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. 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 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

9.8 /10

CVSS v3 : CRITICAL

V3 Legend

Vector :

Exploitability : 3.9 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

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=2004652%2C2019372%2C2021922%2C2022567%2C2022733 Broken Link
https://www.mozilla.org/security/advisories/mfsa2026-20/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-22/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-23/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-24/ 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 (en) Memory safety bugs present in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. 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 < 149, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9. (en) Memory safety bugs present in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. 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 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

25 Mar 2026, 20:56

Type Values Removed Values Added
References () https://bugzilla.mozilla.org/buglist.cgi?bug_id=2004652%2C2019372%2C2021922%2C2022567%2C2022733 - () https://bugzilla.mozilla.org/buglist.cgi?bug_id=2004652%2C2019372%2C2021922%2C2022567%2C2022733 - Broken Link
References () https://www.mozilla.org/security/advisories/mfsa2026-20/ - () https://www.mozilla.org/security/advisories/mfsa2026-20/ - Vendor Advisory
References () https://www.mozilla.org/security/advisories/mfsa2026-22/ - () https://www.mozilla.org/security/advisories/mfsa2026-22/ - Vendor Advisory
References () https://www.mozilla.org/security/advisories/mfsa2026-23/ - () https://www.mozilla.org/security/advisories/mfsa2026-23/ - Vendor Advisory
References () https://www.mozilla.org/security/advisories/mfsa2026-24/ - () https://www.mozilla.org/security/advisories/mfsa2026-24/ - Vendor Advisory
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:*:*:*

25 Mar 2026, 14:16

Type Values Removed Values Added
Summary
  • (es) Errores de seguridad de memoria presentes en Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 y Thunderbird 148. 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 &lt; 149, Firefox ESR &lt; 140.9, Thunderbird &lt; 149 y Thunderbird &lt; 140.9.
CWE CWE-120
CVSS v2 : unknown
v3 : unknown 		v2 : unknown
v3 : 9.8

24 Mar 2026, 21:16

Type Values Removed Values Added
Summary (en) Memory safety bugs present in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. 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 < 149 and Firefox ESR < 140.9. (en) Memory safety bugs present in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. 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 < 149, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
References
  • () https://www.mozilla.org/security/advisories/mfsa2026-23/ -
  • () https://www.mozilla.org/security/advisories/mfsa2026-24/ -

24 Mar 2026, 13:16

Type Values Removed Values Added
New CVE
Information

Published : 2026-03-24 13:16

Updated : 2026-04-13 15:17

NVD link : CVE-2026-4720

Mitre link : CVE-2026-4720

CVE.ORG link : CVE-2026-4720

JSON object : View

Products Affected

mozilla

  • firefox
  • thunderbird
CWE
CWE-120

Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')