CVE-2025-5986
thunderbird - security update
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 was fixed in Thunderbird 128.11.1 and Thunderbird 139.0.2.
How to fix CVE-2025-5986
To remediate CVE-2025-5986, upgrade the affected package to a fixed version below.
- —upgrade to 1:128.12.0esr-1~deb11u1 or later
- —upgrade to 1:128.12.0esr-1~deb11u1 or later
- —upgrade to 1:128.12.0esr-1~deb12u1 or later
Is CVE-2025-5986 being exploited?
Low — EPSS is 0.6%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- from 0, < 1:128.12.0esr-1~deb11u1
- from 0, < 1:128.12.0esr-1~deb11u1
- from 0, < 1:128.12.0esr-1~deb12u1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H |