Request forgery via news: links

Summary

Clicking a news: or snews: link that referenced a message-ID made Thunderbird connect, without asking, to the host and port given in the link, even if it was not a configured news server. Line breaks in the message-ID were sent to the server unmodified, so a crafted link could send arbitrary commands to services reachable from the user's network. In addition, snews: links to such servers connected without TLS. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.

Remediation

1. Inventory every Mozilla Thunderbird deployment, including staging.
2. No fixed version appears in the public sources yet. Check the references below and the vendor directly.

References

• Referencehttps://bugzilla.mozilla.org/show_bug.cgi?id=2077789
• Referencehttps://www.mozilla.org/security/advisories/mfsa2026-121/
• Referencehttps://www.mozilla.org/security/advisories/mfsa2026-122/