CVE-2021-3996

low-risk

Published 2022-08-23

A 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 a local user on a vulnerable system to unmount other users' filesystems that are either world-writable themselves (like /tmp) or mounted in a world-writable directory. An attacker may use this flaw to cause a denial of service to applications that use the affected filesystems.

Do I need to act?

0.23% chance of exploitation

EPSS score — low exploit probability

Not on CISA KEV list

No confirmed active exploitation reported to CISA

Patch status unknown

Check vendor advisories for fix availability and mitigation guidance

CVSS 5.5/10 Medium

LOCAL / LOW complexity

Affected Products (2)

Util-Linux

Fedora

Affected Vendors

Kernel Fedoraproject

References (20)

Third Party Advisory http://packetstormsecurity.com/files/170176/snap-confine-must_mkdir_and_open_wit...

Mailing List http://seclists.org/fulldisclosure/2022/Dec/4

Mailing List http://www.openwall.com/lists/oss-security/2022/11/30/2

Issue Tracking https://access.redhat.com/security/cve/CVE-2021-3996

Issue Tracking https://bugzilla.redhat.com/show_bug.cgi?id=2024628

Patch https://github.com/util-linux/util-linux/commit/166e87368ae88bf31112a30e078cceae...

Release Notes https://mirrors.edge.kernel.org/pub/linux/utils/util-linux/v2.37/v2.37.3-Release...

https://security.gentoo.org/glsa/202401-08

Broken Link https://security.netapp.com/advisory/ntap-20221209-0002/

Exploit https://www.openwall.com/lists/oss-security/2022/01/24/2