CVE-2025-3932

MEDIUM 6.5

Tracking Links in Attachments Bypassed Remote Content Blocking

CVSS Score

6.5

EPSS Score

0.0%

EPSS Percentile

0th

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 pages listed in the X-Mozilla-External-Attachment-URL header of an email. This vulnerability was fixed in Thunderbird 128.10.1 and Thunderbird 138.0.1.

Vendor	mozilla
Product	thunderbird
Ecosystems	Browser JavaScript
Industries	Technology
Published	May 14, 2025
Last Updated	Apr 13, 2026

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Affected Versions

Mozilla / Thunderbird

All versions affected

References

NVD ↗ CVE.org ↗ EPSS Data ↗

bugzilla.mozilla.org: https://bugzilla.mozilla.org/show_bug.cgi?id=1960412 mozilla.org: https://www.mozilla.org/security/advisories/mfsa2025-34/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2025-35/ lists.debian.org: https://lists.debian.org/debian-lts-announce/2025/05/msg00022.html

Credits

Dario Weißer