CVE-2026-74990
criticalInternally found bugs present in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153.
Vendor / product: Mozilla — firefox
Internally found bugs present in Firefox ESR 115.38, Firefox ESR 140.13, Firefox ESR 153.0 and Firefox 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
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 (134c704f-9b21-4f2e-91b3-4a467353bcc0)
Timeline (UTC)
Published: 2026-08-18 13:17
Modified: 2026-10-28 17:18
NVD status: Modified
Last synced 13 hours ago
Verified against the source API 2026-10-28 17:38 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 <115.39.0, ≥116.0 <140.14.0, ≥141.0 <153.1.0
mozilla / thunderbird <140.14.0, ≥141.0 <153.1.0
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/mfsa2026-74/
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-75/
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-76/
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-77/
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-78/
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-79/
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-80/
References
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=2045762%2C2052401%2C2058208 security@mozilla.org
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=2045774%2C2048490%2C2050864%2C2053159%2C20... security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-74/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-75/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-76/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-77/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-78/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-79/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-80/ security@mozilla.org
Data sources
NVD CVE API 2.0 — fetched 2026-10-28 17:38 UTC · record ↗