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Vulnerability record · CVE-2025-11721 · published 14 October 2025

CVE-2025-11721: Mozilla firefox memory buffer overflow vulnerability

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.

9.8 CVSS 3.1 Critical EPSS 0.37% · top 72.3% CWE-119 · Memory buffer overflow
9.8CVSS 3.1 base score
0.37%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
3References
17 Jun 2026Last modified by NVD

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

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://bugzilla.mozilla.org/show_bug.cgi?id=1986816 Issue TrackingPermissions Required
https://www.mozilla.org/security/advisories/mfsa2025-81/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-84/ Vendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2025-11721), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.