In util-linux before 2.32-rc1, bash-completion/umount allows local users to gain privileges by embedding shell commands in a mountpoint name, which is mishandled during a umount command (within Bash) by a different user, as demonstrated by logging in as root and entering umount followed by a tab character for autocompletion.

Affected: Ubuntu:18.04:LTS: util-linux

It was discovered that the umount bash completion script shipped in util-linux incorrectly handled certain mountpoints. If a local attacker were able to create arbitrary mountpoints, another user could be tricked into executing arbitrary code when attempting to run the umount command with bash completion.