CVE-2025-3932 Tracking Links in Attachments Bypassed Remote Content Blocking

It was possible to craft an email that showed a tracking link as an attachment. If the user attempted to open the attachment, Thunderbird automatically accessed the link. The configuration to block remote content did not prevent that. Thunderbird has been fixed to no longer allow access to web...

CVE-2025-3909: Product UI does not Warn User of Unsafe Actions

Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context. By crafting a nested email attachment message/rfc822 and setting its content type to application/pdf, Thunderbird may incorrectly render it as HTML when opened,...

CVE-2025-3932: Authentication Bypass Using an Alternate Path or Channel

It was possible to craft an email that showed a tracking link as an attachment. If the user attempted to open the attachment, Thunderbird automatically accessed the link. The configuration to block remote content did not prevent that. Thunderbird has been fixed to no longer allow access to web...

Mozilla Thunderbird < 137.0.2

The version of Thunderbird installed on the remote Windows host is prior to 137.0.2. It is, therefore, affected by multiple vulnerabilities as referenced in the mfsa2025-26 advisory. - When an email contains multiple attachments with external links via the X-Mozilla-External-Attachment-URL header...

CVE-2025-3523: User Interface (UI) Misrepresentation of Critical Information

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...

CVE-2025-3522: URL Redirection to Untrusted Site

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 validate...