CVE-2026-84637

Name	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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
thunderbird (PTS)	bookworm	1:140.12.0esr-1~deb12u1	fixed
	bookworm (security)	1:140.14.0esr-1~deb12u1	fixed
	trixie	1:140.12.0esr-1~deb13u1	fixed
	trixie (security)	1:140.14.0esr-1~deb13u1	fixed
	forky, sid	1:140.14.0esr-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
thunderbird	source	(unstable)	(not affected)

- thunderbird <not-affected> (Windows-specific)
https://www.mozilla.org/en-US/security/advisories/mfsa2026-78/#CVE-2026-84637