Vulnerability · NVD

CVE-2026-0891

CVE-2026-0891, high severity (CVSS 8.1): 2 tracked apps concerned, all fixed or indeterminable on their current version.

Severity (CVSS): 8.1
Exploitation: 0.5 %
Tracked apps: 2
Still exposed: 0

Published on 2026-01-13

Memory safety bugs present in Firefox ESR 140.6, Thunderbird ESR 140.6, Firefox 146 and Thunderbird 146. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 147, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.

Attack vector : Network No privileges required No user interaction

Show raw CVSS vector

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

EPSS 0.48% exploit very unlikely percentile 38.9%

Tracked apps referencing this CVE

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

Mozilla Firefox Windows winget:Mozilla.Firefox

Affected <140.7.0 Fixed in 140.7.0 Latest tracked 156.0.1 patched

Observed affected builds (127)

140.0.4 140.0.2 140.0.1 140.0 139.0.4 139.0.1 139.0 138.0.4 138.0.3 138.0.1 138.0 137.0.2 137.0.1 137.0 136.0.4 136.0.3 136.0.2 136.0.1 136.0 135.0.1 135.0 134.0.2 134.0.1 134.0 133.0.3 133.0 132.0.2 132.0.1 132.0 131.0.3 +97 · see history
Mozilla Thunderbird Windows winget:Mozilla.Thunderbird

Affected <140.7.0 Fixed in 140.7.0 Latest tracked 156.0.1 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 (4)

Vendor	Product	Platform	Versions	CPE 2.3 URI
mozilla	firefox All platforms (wildcard)	All platforms (wildcard)	<140.7.0	cpe:2.3:a:mozilla:firefox:::::esr:::*
mozilla	firefox All platforms (wildcard)	All platforms (wildcard)	<147.0	cpe:2.3:a:mozilla:firefox:::::-:::*
mozilla	thunderbird All platforms (wildcard)	All platforms (wildcard)	<140.7.0	cpe:2.3:a:mozilla:thunderbird:::::esr:::*
mozilla	thunderbird All platforms (wildcard)	All platforms (wildcard)	<147.0	cpe:2.3:a:mozilla:thunderbird:::::-:::*

View on NVD ↗ Advisory · www.mozilla.org

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