CVE-2025-3522
6.3
MEDIUM
CVSS 3.1
EPSS 0.10%
Description
Thunderbird processes the X-Mozilla-External-Attachment-URL header to handle attachments which can be hosted externally. When an email is opened, Thunderbird accesses the specified URL to determine file size, and navigates to it when the user clicks the attachment. Because the URL is not validated or sanitized, it can reference internal resources like chrome:// or SMB share file:// links, potentially leading to hashed Windows credential leakage and opening the door to more serious security issues. This vulnerability was fixed in Thunderbird 137.0.2 and Thunderbird 128.9.2.
How to fix CVE-2025-3522
To remediate CVE-2025-3522, upgrade the affected package to a fixed version below.
- —upgrade to 1:128.10.1esr-1~deb11u1 or later
Is CVE-2025-3522 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 1:128.10.1esr-1~deb11u1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM6.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L |