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.
https://www.debian.org/security/2018/dsa-4134
https://usn.ubuntu.com/4512-1/
https://github.com/karelzak/util-linux/issues/539
https://github.com/karelzak/util-linux/commit/75f03badd7ed9f1dd951863d75e756883d3acc55
Published: 2018-03-07
Updated: 2020-09-25
Base Score: 7.2
Vector: CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C
Severity: High
Base Score: 7.8
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity: High
Base Score: 9.3
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Severity: Critical