Vulnerability · NVD

CVE-2026-74990

CVE-2026-74990, critical severity (CVSS 9.8): 1 tracked app concerned, all fixed or indeterminable on their current version.

Severity (CVSS): 9.8
Exploitation: 0.6 %
Tracked apps: 1
Still exposed: 0

Published on 2026-08-18

Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 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.

Attack vector : Network No privileges required No user interaction

Show raw CVSS vector

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

EPSS 0.56% exploit very unlikely percentile 44.0%

Tracked apps referencing this CVE

For each app: the affected range, the fixing version, and where the tracked app stands today.

Mozilla Thunderbird Windows winget:Mozilla.Thunderbird

Affected <140.14.0 Fixed in 140.14.0 Latest tracked 154.0 patched

Observed affected builds (100)

140.0.1 140.0 139.0.2 139.0.1 139.0 138.0.2 138.0.1 138.0 137.0.2 137.0.1 137.0 136.0.1 136.0 115.14.0 115.13.0 115.12.2 115.12.1 115.11.1 115.11.0 115.10.2 115.10.1 115.10.0 115.9.0 115.8.1 115.8.0 115.7.0 115.6.1 115.6.0 115.5.2 115.5.1 +70 · see history

Vulnerable CPE configurations (2)

Vendor	Product	Platform	Versions	CPE 2.3 URI
mozilla	thunderbird All platforms (wildcard)	All platforms (wildcard)	<140.14.0	cpe:2.3:a:mozilla:thunderbird::::::::
mozilla	thunderbird All platforms (wildcard)	All platforms (wildcard)	≥141.0 <153.1.0	cpe:2.3:a:mozilla:thunderbird::::::::

View on NVD ↗ Advisory · www.mozilla.org