CVE-2019-19234: In Sudo through 1.8.29, the fact that a user has been blocked (e.g., by using the ! character in the shadow file instead of a password hash) is not considered…

high7.5CVSS 3.1

AVNACLPRNUINSUCNIHAN

In Sudo through 1.8.29, the fact that a user has been blocked (e.g., by using the ! character in the shadow file instead of a password hash) is not considered, allowing an attacker (who has access to a Runas ALL sudoer account) to impersonate any blocked user. NOTE: The software maintainer believes that this CVE is not valid. Disabling local password authentication for a user is not the same as disabling all access to that user--the user may still be able to login via other means (ssh key, kerberos, etc). Both the Linux shadow(5) and passwd(1) manuals are clear on this. Indeed it is a valid use case to have local accounts that are _only_ accessible via sudo and that cannot be logged into with a password. Sudo 1.8.30 added an optional setting to check the _shell_ of the target user (not the encrypted password!) against the contents of /etc/shells but that is not the same thing as preventing access to users with an invalid password hash

Affected

6 ranges

Vendor	Product	Version range	Fixed in
debian	sudo	< sudo 1.8.31-1 (bookworm)	sudo 1.8.31-1 (bookworm)
sudo	sudo	<= 1.8.29	—
sudo_project	sudo	>= 0 < 1.8.31-1	1.8.31-1
sudo_project	sudo	>= 0 < 1.8.31-1	1.8.31-1
sudo_project	sudo	>= 0 < 1.8.31-1	1.8.31-1
sudo_project	sudo	>= 0 < 1.8.31-1	1.8.31-1

CVSS provenance

nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

osv7.5HIGH