CVE-2021-3996

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.

This issue did not affect the versions of util-linux as shipped with Red Hat Enterprise Linux 6, 7, and 8 as they ship an older version which does not allow unprivileged users to unmount FUSE mount points for the current user (e.g. the vulnerable function is_fuse_usermount() does not exist).

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.