Vulnerability · NVD

CVE-2025-3909

CVE-2025-3909, high severity (CVSS 8.1): 1 tracked app concerned, all fixed or indeterminable on their current version.

Severity (CVSS): 8.1
Exploitation: 0.4 %
Tracked apps: 1
Still exposed: 0

Published on 2025-05-14

Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context. By crafting a nested email attachment (message/rfc822) and setting its content type to application/pdf, Thunderbird may incorrectly render it as HTML when opened, allowing the embedded JavaScript to run without requiring a file download. This behavior relies on Thunderbird auto-saving the attachment to /tmp and linking to it via the file:/// protocol, potentially enabling JavaScript execution as part of the HTML. This vulnerability was fixed in Thunderbird 128.10.1 and Thunderbird 138.0.1.

Attack vector : Network No privileges required

Show raw CVSS vector

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

EPSS 0.44% exploit very unlikely percentile 35.8%

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 <128.10.1 Fixed in 128.10.1 Latest tracked 157.0.1 patched

Observed affected builds (87)

115.14.0 115.13.0 115.12.2 115.12.1 115.11.1 115.11.0 115.10.2 115.10.1 115.10.0 115.9.0 115.8.1 115.8.0 115.7.0 115.6.1 115.6.0 115.5.2 115.5.1 115.4.2 115.4.1 115.3.3 115.3.2 115.3.1 115.3.0 115.2.3 115.2.2 115.0 102.15.0 102.14.0 102.13.0 102.12.0 +57 · see history

Vulnerable CPE configurations (2)

Vendor	Product	Platform	Versions	CPE 2.3 URI
mozilla	thunderbird All platforms (wildcard)	All platforms (wildcard)	<128.10.1	cpe:2.3:a:mozilla:thunderbird::::::::
mozilla	thunderbird All platforms (wildcard)	All platforms (wildcard)	≥129.0 <138.0.1	cpe:2.3:a:mozilla:thunderbird::::::::

View on NVD ↗ Advisory · www.mozilla.org

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