Critical severity · published Oct 14, 2025
CVE-2025-11721
Memory safety bug fixed in Firefox 144 and Thunderbird 144
9.8
CVSS
0.4%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 30% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FI
Firefox · Mozilla
143.0 before 144.0 · source: NVD
TH
Thunderbird · Mozilla
143.0 before 144.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-11721
CVE.org
https://www.cve.org/CVERecord?id=CVE-2025-11721
Issue Tracking
https://bugzilla.mozilla.org/show_bug.cgi?id=1986816
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-81/
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-84/
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