CVE-2021-4197

NameCVE-2021-4197
DescriptionAn unprivileged write to the file handler flaw in the Linux kernel's control groups and namespaces subsystem was found in the way users have access to some less privileged process that are controlled by cgroups and have higher privileged parent process. It is actually both for cgroup2 and cgroup1 versions of control groups. A local user could use this flaw to crash the system or escalate their privileges on the system.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
ReferencesDSA-5127-1, DSA-5173-1, ELA-652-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)jessie, jessie (lts)3.16.84-1vulnerable
stretch (security), stretch (lts), stretch4.9.320-2vulnerable
buster, buster (security)4.19.249-2fixed
bullseye5.10.140-1fixed
bullseye (security)5.10.136-1fixed
sid, bookworm5.19.6-1fixed
linux-4.19 (PTS)jessie, jessie (lts)4.19.249-2~deb8u1fixed
stretch (security)4.19.232-1~deb9u1vulnerable
stretch (lts), stretch4.19.249-2~deb9u1fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcejessie(unfixed)end-of-life
linuxsourcestretch(unfixed)end-of-life
linuxsourcebuster4.19.249-2DSA-5173-1
linuxsourcebullseye5.10.113-1DSA-5127-1
linuxsource(unstable)5.15.15-1
linux-4.19sourcejessie4.19.249-2~deb8u1ELA-652-1
linux-4.19sourcestretch4.19.249-2~deb9u1ELA-652-1

Notes

https://lore.kernel.org/lkml/20211209214707.805617-1-tj@kernel.org/T/
https://bugzilla.redhat.com/show_bug.cgi?id=2035652

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