CVE-2025-11721

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 3.1

9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

0.4% chance of exploitation in the next 30 days; higher than 30% of CVEs (scores of 2026-10-25)

CWE

CWE-119

Published

2025-10-14

Modified

2026-10-18

Record from

the NVD, synced 2026-10-19

Affected

• mozilla:firefox
• mozilla:thunderbird

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1986816
• https://www.mozilla.org/security/advisories/mfsa2025-81/
• https://www.mozilla.org/security/advisories/mfsa2025-84/

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