CVE-2021-4126

Name	CVE-2021-4126
Description	When receiving an OpenPGP/MIME signed email message that contains an additional outer MIME message layer, for example a message footer added by a mailing list gateway, Thunderbird only considered the inner signed message for the signature validity. This gave the false impression that the additional contents were also covered by the digital signature. Starting with Thunderbird version 91.4.1, only the signature that belongs to the top level MIME part will be considered for the displayed status. This vulnerability affects Thunderbird < 91.4.1.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DLA-2874-1, DSA-5034-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
thunderbird (PTS)	jessie, jessie (lts)	1:68.9.0-1~deb8u2	vulnerable
	stretch (security), stretch (lts), stretch	1:91.10.0-1~deb9u1	fixed
	buster (security), buster, buster (lts)	1:115.12.0-1~deb10u1	fixed
	bullseye	1:115.12.0-1~deb11u1	fixed
	bullseye (security)	1:128.5.0esr-1~deb11u1	fixed
	bookworm	1:115.16.0esr-1~deb12u1	fixed
	bookworm (security)	1:128.5.0esr-1~deb12u1	fixed
	sid, trixie	1:128.5.2esr-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin
thunderbird	source	jessie	(unfixed)	end-of-life
thunderbird	source	stretch	1:91.4.1-1~deb9u1		DLA-2874-1
thunderbird	source	buster	1:91.4.1-1~deb10u1		DSA-5034-1
thunderbird	source	bullseye	1:91.4.1-1~deb11u1		DSA-5034-1
thunderbird	source	(unstable)	1:91.4.1-1

https://www.mozilla.org/en-US/security/advisories/mfsa2021-55/#CVE-2021-4126