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. This vulnerability affects Thunderbird < 137.0.2 and Thunderbird < 128.9.2.
Problem types
User Interface (UI) Misrepresentation of attachment URL
Product status
Credits
Dario Weißer
References
bugzilla.mozilla.org/show_bug.cgi?id=1958385
www.mozilla.org/security/advisories/mfsa2025-26/
www.mozilla.org/security/advisories/mfsa2025-27/
