CVE-2021-3864

Name	CVE-2021-3864
Description	A flaw was found in the way the dumpable flag setting was handled when certain SUID binaries executed its descendants. The prerequisite is a SUID binary that sets real UID equal to effective UID, and real GID equal to effective GID. The descendant will then have a dumpable value set to 1. As a result, if the descendant process crashes and core_pattern is set to a relative value, its core dump is stored in the current directory with uid:gid permissions. An unprivileged local user with eligible root SUID binary could use this flaw to place core dumps into root-owned directories, potentially resulting in escalation of privileges.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, 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
linux (PTS)	jessie, jessie (lts)	3.16.84-1	vulnerable
	stretch (security)	4.9.320-2	vulnerable
	stretch (lts), stretch	4.9.320-3	vulnerable
	buster	4.19.249-2	vulnerable
	buster (security)	4.19.304-1	vulnerable
	bullseye	5.10.209-2	vulnerable
	bullseye (security)	5.10.205-2	vulnerable
	bookworm	6.1.76-1	vulnerable
	bookworm (security)	6.1.85-1	vulnerable
	trixie	6.6.15-2	vulnerable
	sid	6.7.9-2	vulnerable

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

Package	Type	Release	Fixed Version	Urgency
linux	source	jessie	(unfixed)	end-of-life
linux	source	stretch	(unfixed)	end-of-life
linux	source	(unstable)	(unfixed)

https://www.openwall.com/lists/oss-security/2021/10/20/2