CVE-2025-5986 is a medium-severity vulnerability affecting Mozilla Thunderbird versions prior to 128.11.1 and 139.0.2. It allows a crafted HTML email with mailbox:/// links to trigger automatic, unsolicited downloads of PDF files to a user's desktop or home directory, even with auto-saving disabled. This can lead to denial of service by filling the disk with garbage data or credential leakage via SMB links when the email is viewed in HTML mode. The vulnerability has a CVSS score of 6.5 (Medium) due to its network attack vector and low attack complexity, though user interaction is required. There is currently no known active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or KEV listing, with minimal community discussion and media coverage.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
< 128.11.1CPE matchmatch criteria | cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:* | ||
>= 135.0, < 139.0.2CPE matchmatch criteria | cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:* |
CVSS version used by this source: 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.
The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.