Critical 9.8Published Oct 14, 2025

CVE-2025-11721Memory safety bug present in Firefox 143 and Thunderbird 143.

Updated under an hour ago (2026-10-19 08:30 UTC)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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: 9.8 CRITICAL (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-119
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Not given
NVD analysis: Modified
Record last updated: Oct 18, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

mozilla firefox mozilla:firefox	from 143.0 before 144.0	NVD
mozilla thunderbird mozilla:thunderbird	from 143.0 before 144.0	NVD

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1986816issue-tracking, permissions-required
https://www.mozilla.org/security/advisories/mfsa2025-81/vendor-advisory
https://www.mozilla.org/security/advisories/mfsa2025-84/vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.