Vulnerability Description
Memory safety bug present in Firefox 143 and Thunderbird 143. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 144 and Thunderbird 144.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | >= 143.0, < 144.0 |
| Mozilla | Thunderbird | >= 143.0, < 144.0 |
Related Weaknesses (CWE)
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1986816Issue TrackingPermissions Required
- https://www.mozilla.org/security/advisories/mfsa2025-81/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-84/Vendor Advisory
FAQ
What is CVE-2025-11721?
CVE-2025-11721 is a vulnerability with a CVSS score of 9.8 (CRITICAL). Memory safety bug present in Firefox 143 and Thunderbird 143. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code....
How severe is CVE-2025-11721?
CVE-2025-11721 has been rated CRITICAL with a CVSS base score of 9.8/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2025-11721?
Check the references section above for vendor advisories and patch information. Affected products include: Mozilla Firefox, Mozilla Thunderbird.