Vulnerability · NVD

CVE-2025-5986

MEDIUM 6.5 Published on 2025-06-11

A crafted HTML email using mailbox:/// links can trigger automatic, unsolicited downloads of .pdf files to the user's desktop or home directory without prompting, even if auto-saving is disabled. This behavior can be abused to fill the disk with garbage data (e.g. using /dev/urandom on Linux) or to leak Windows credentials via SMB links when the email is viewed in HTML mode. While user interaction is required to download the .pdf file, visual obfuscation can conceal the download trigger. Viewing the email in HTML mode is enough to load external content. This vulnerability was fixed in Thunderbird 128.11.1 and Thunderbird 139.0.2.

Attack vector : Network No privileges required

Show raw CVSS vector

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

EPSS 0.51% exploit very unlikely percentile 40.7%

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 ≥135.0 <139.0.2 Fixed in 139.0.2 Latest tracked 153.0.2 patched

Vulnerable CPE configurations (2)

Vendor	Product	Platform	Versions	CPE 2.3 URI
mozilla	thunderbird All platforms (wildcard)	All platforms (wildcard)	<128.11.1	cpe:2.3:a:mozilla:thunderbird:::::-:::*
mozilla	thunderbird All platforms (wildcard)	All platforms (wildcard)	≥135.0 <139.0.2	cpe:2.3:a:mozilla:thunderbird:::::-:::*

View on NVD ↗ Advisory · www.mozilla.org