** DISPUTED ** 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.
mdeslaurupstream sudo has disputed this CVE, sudo works as intended and
as documented, so marking this as not-affected.
Source: sudo (LP Ubuntu Debian)
Upstream:released (1.8.30)
Ubuntu 12.04 ESM (Precise Pangolin):not-affected
Ubuntu 14.04 ESM (Trusty Tahr):not-affected
Ubuntu 16.04 LTS (Xenial Xerus):not-affected
Ubuntu 18.04 LTS (Bionic Beaver):not-affected
Ubuntu 20.04 LTS (Focal Fossa):released (1.8.31-1ubuntu1)
Ubuntu 20.10 (Groovy Gorilla):released (1.8.31-1ubuntu1)
More Information

Updated: 2020-07-28 20:07:15 UTC (commit d26b6ca9f5b3adb89bb036ce73ae7dab894935ec)