CVE-2025-11721
criticalMemory safety bug present in Firefox 143 and Thunderbird 143.
Vendor / product: Mozilla — firefox
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
9.8 (CVSS v3.1)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Severity source: NVD CVSS v3.1 (nvd@nist.gov)
Timeline (UTC)
Published: 2025-10-14 13:15
Modified: 2026-10-18 21:10
NVD status: Modified
Last synced 2 days ago
Verified against the source API 2026-10-27 07:06 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).
Affected products
mozilla / firefox ≥143.0 <144.0
mozilla / thunderbird ≥143.0 <144.0
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2025-81/
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2025-84/
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1986816 security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2025-81/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2025-84/ security@mozilla.org
Data sources
NVD CVE API 2.0 — fetched 2026-10-27 07:06 UTC · record ↗