CVE-2026-103500

Name	CVE-2026-103500
Description	An attacker could cause a heap buffer overflow by getting a user to open an email that is greater than or equal to 2GB in size. This vulnerability was fixed in Thunderbird 157, Thunderbird 140.17, and Thunderbird 153.4.
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	vulnerable
	bookworm (security)	1:140.17.0esr-1~deb12u1	vulnerable
	trixie	1:140.12.0esr-1~deb13u1	vulnerable
	trixie (security)	1:140.16.0esr-1~deb13u1	vulnerable
	forky	1:140.14.0esr-1	vulnerable
	sid	1:153.3.0esr-2	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
thunderbird	source	(unstable)	(unfixed)

https://www.mozilla.org/en-US/security/advisories/mfsa2026-103/#CVE-2026-103500