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OpenAdvisories
High DSA-5921-1 3 CVEs

thunderbird - security update

Published May 16, 2025 · Updated Mar 9, 2026

Fixed packages 1

ReleasePackageFixed in
Debian · 12 thunderbird 1:128.10.1esr-1~deb12u1

Vulnerabilities 3

  • High 8.1

    JavaScript Execution via Spoofed PDF Attachment and file:/// Link

    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 inco…

  • High 7.5

    Sender Spoofing via Malformed From Header in Thunderbird

    Thunderbird parses addresses in a way that can allow sender spoofing in case the server allows an invalid From address to be used. For example, if the From header contains an (invalid) value "Spoofed Name ", Thunderbird treats spoofed@example.com as the actua…

  • Medium 6.5

    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 fix…