Mozilla Foundation Security Advisory 2025-26
Security Vulnerabilities fixed in Thunderbird 137.0.2
- Announced
- April 15, 2025
- Impact
- high
- Products
- Thunderbird
- Fixed in
-
- Thunderbird 137.0.2
#CVE-2025-3522: Leak of hashed Window credentials via crafted attachment URL
- Reporter
- Dario Weißer
- Impact
- high
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.
References
#CVE-2025-2830: Information Disclosure of /tmp directory listing
- Reporter
- Dario Weißer
- Impact
- high
Description
By crafting a malformed file name for an attachment in a multipart message, an attacker can trick Thunderbird into including a directory listing of /tmp when the message is forwarded or edited as a new message. This vulnerability could allow attackers to disclose sensitive information from the victim's system. This vulnerability is not limited to Linux; similar behavior has been observed on Windows as well.
References
#CVE-2025-3523: User Interface (UI) Misrepresentation of attachment URL
- Reporter
- Dario Weißer
- Impact
- low
Description
When an email contains multiple attachments with external links via the X-Mozilla-External-Attachment-URL header, only the last link is shown when hovering over any attachment. Although the correct link is used on click, the misleading hover text could trick users into downloading content from untrusted sources.