CVE-2021-23960

Name	CVE-2021-23960
Description	Performing garbage collection on re-declared JavaScript variables resulted in a user-after-poison, and a potentially exploitable crash. This vulnerability affects Firefox < 85, Thunderbird < 78.7, and Firefox ESR < 78.7.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
References	DLA-2539-1, DLA-2541-1, DSA-4840-1, DSA-4842-1
NVD severity	medium

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
firefox (PTS)	sid	87.0-2	fixed
firefox-esr (PTS)	stretch	68.10.0esr-1~deb9u1	vulnerable
	stretch (security)	78.9.0esr-1~deb9u1	fixed
	buster	78.8.0esr-1~deb10u1	fixed
	buster (security)	78.9.0esr-1~deb10u1	fixed
	bullseye, sid	78.9.0esr-1	fixed
thunderbird (PTS)	stretch	1:68.10.0-1~deb9u1	vulnerable
	stretch (security)	1:78.9.0-1~deb9u1	fixed
	buster	1:78.6.0-1~deb10u1	vulnerable
	buster (security)	1:78.9.0-1~deb10u1	fixed
	bullseye, sid	1:78.9.0-1	fixed

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

Package	Type	Release	Fixed Version	Origin
firefox	source	(unstable)	85.0-1
firefox-esr	source	stretch	78.7.0esr-1~deb9u1	DLA-2539-1
firefox-esr	source	buster	78.7.0esr-1~deb10u1	DSA-4840-1
firefox-esr	source	(unstable)	78.7.0esr-1
thunderbird	source	stretch	1:78.7.0-1~deb9u1	DLA-2541-1
thunderbird	source	buster	1:78.7.0-1~deb10u1	DSA-4842-1
thunderbird	source	(unstable)	1:78.7.0-1

Notes

https://www.mozilla.org/en-US/security/advisories/mfsa2021-04/#CVE-2021-23960
https://www.mozilla.org/en-US/security/advisories/mfsa2021-03/#CVE-2021-23960
https://www.mozilla.org/en-US/security/advisories/mfsa2021-05/#CVE-2021-23960