Vulnerability · NVD

CVE-2026-84120

CVE-2026-84120, medium severity (CVSS 5.4): 2 tracked apps concerned, all fixed or indeterminable on their current version.

Severity (CVSS): 5.4
Exploitation: 0.2 %
Tracked apps: 2
Still exposed: 0

Published on 2026-09-01

Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

Attack vector : Network No privileges required

Show raw CVSS vector

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

EPSS 0.22% exploit very unlikely percentile 11.5%

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 <115.40.0 Fixed in 115.40.0 Latest tracked 157.0.1 patched

Observed affected builds (57)

115.0.3 115.0.2 115.0.1 115.0 114.0.2 114.0.1 113.0.2 113.0.1 113.0 112.0.2 112.0.1 112.0 111.0.1 111.0 110.0.1 110.0 109.0.1 109.0 108.0.2 108.0.1 108.0 107.0.1 107.0 106.0.5 106.0.4 106.0.3 106.0.2 106.0.1 106.0 105.0.3 +27 · see history
Mozilla Thunderbird Windows winget:Mozilla.Thunderbird

Affected <140.15.0 Fixed in 140.15.0 Latest tracked 158.0 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 (7)

Vendor	Product	Platform	Versions	CPE 2.3 URI
mozilla	firefox All platforms (wildcard)	All platforms (wildcard)	<115.40.0	cpe:2.3:a:mozilla:firefox::::::::
mozilla	firefox All platforms (wildcard)	All platforms (wildcard)	≥116.0 <140.15.0	cpe:2.3:a:mozilla:firefox::::::::
mozilla	firefox All platforms (wildcard)	All platforms (wildcard)	≥141.0.0 <153.2.0	cpe:2.3:a:mozilla:firefox::::::::
mozilla	firefox All platforms (wildcard)	All platforms (wildcard)	≥154.0.0 <155.0.0	cpe:2.3:a:mozilla:firefox::::::::
mozilla	thunderbird All platforms (wildcard)	All platforms (wildcard)	<140.15.0	cpe:2.3:a:mozilla:thunderbird::::::::
mozilla	thunderbird All platforms (wildcard)	All platforms (wildcard)	≥141.0 <153.2.0	cpe:2.3:a:mozilla:thunderbird::::::::
mozilla	thunderbird All platforms (wildcard)	All platforms (wildcard)	≥154.0 <155.0	cpe:2.3:a:mozilla:thunderbird::::::::

View on NVD ↗ Advisory · www.mozilla.org

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