CVE-2021-3995

NameCVE-2021-3995
DescriptionA logic error was found in the libmount library of util-linux in the function that allows an unprivileged user to unmount a FUSE filesystem. This flaw allows an unprivileged local attacker to unmount FUSE filesystems that belong to certain other users who have a UID that is a prefix of the UID of the attacker in its string form. An attacker may use this flaw to cause a denial of service to applications that use the affected filesystems.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDSA-5055-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
util-linux (PTS)jessie, jessie (lts)2.26.2+really2.25.2-6+deb8u2fixed
stretch (security)2.29.2-1+deb9u1fixed
stretch (lts), stretch2.29.2-1+deb9u3fixed
buster (security), buster, buster (lts)2.33.1-0.1+deb10u1fixed
bullseye (security), bullseye2.36.1-8+deb11u2fixed
bookworm2.38.1-5+deb12u2fixed
bookworm (security)2.38.1-5+deb12u1fixed
sid, trixie2.40.2-12fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
util-linuxsourcejessie(not affected)
util-linuxsourcestretch(not affected)
util-linuxsourcebuster(not affected)
util-linuxsourcebullseye2.36.1-8+deb11u1DSA-5055-1
util-linuxsource(unstable)2.37.3-1

Notes

[buster] - util-linux <not-affected> (Vulnerable code introduced later)
[stretch] - util-linux <not-affected> (Vulnerable code introduced later)
Introduced by: https://github.com/util-linux/util-linux/commit/5fea669e9ef0a08804f72bb40f859f239f68c30a (v2.34-rc1)
Fixed by: https://github.com/util-linux/util-linux/commit/f3db9bd609494099f0c1b95231c5dfe383346929 (v2.37.3)
https://mirrors.edge.kernel.org/pub/linux/utils/util-linux/v2.37/v2.37.3-ReleaseNotes
https://www.openwall.com/lists/oss-security/2022/01/24/2
[jessie] - util-linux <not-affected> (Vulnerable code introduced later)

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