CVE-2021-3995 Missing authorization in util-linux

What is CVE-2021-3995?

CVE-2021-3995 is a medium-severity missing authorization vulnerability in Fedoraproject Fedora, published on 23 Aug 2022. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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 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.

Weakness: CWE-552

Which versions are affected by CVE-2021-3995?

It affects 2 products.

Products include Fedoraproject Fedora, Kernel Util-Linux.

How do I fix CVE-2021-3995?

Apply the vendor's patch.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

Is CVE-2021-3995 being exploited?

There is no known exploitation of CVE-2021-3995 in the wild and no public exploit code.

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All Fedoraproject Fedora vulnerabilities

Sources

• CVE record
• NVD
• OSV
• How this page is made

Also known as ALPINE-CVE-2021-3995, CLEANSTART-2026-WY70417, DEBIAN-CVE-2021-3995, JLSEC-2025-192, UBUNTU-CVE-2021-3995.