CVE-2025-5986

6.5 MEDIUM
Published: June 11, 2025 Modified: November 03, 2025

Description

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 affects Thunderbird < 128.11.1 and Thunderbird < 139.0.2.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2025-49/
Source: security@mozilla.org
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-50/
Source: security@mozilla.org
Vendor Advisory

4 reference(s) from NVD

Quick Stats

CVSS v3 Score
6.5 / 10.0
EPSS (Exploit Probability)
0.1%
21th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

mozilla