CVE-2026-84637

Description

Malicious calendar invitations could use file URI attachments to launch local or network-hosted executables on Windows, bypassing Thunderbird's normal executable attachment protections. With the new invitation display enabled, the attachment could also appear under a misleading filename. This vulnerability was fixed in Thunderbird 154 and Thunderbird 153.2.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=2043878
• https://www.mozilla.org/security/advisories/mfsa2026-78/
• https://www.mozilla.org/security/advisories/mfsa2026-88/