CVE-2019-19234 Affecting sudo package, versions <1.8.31-1ubuntu1


Severity

Recommended
low

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.76% (82nd percentile)

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  • Snyk IDSNYK-UBUNTU2004-SUDO-580831
  • published22 Dec 2019
  • disclosed19 Dec 2019

Introduced: 19 Dec 2019

CVE-2019-19234  (opens in a new tab)

How to fix?

Upgrade Ubuntu:20.04 sudo to version 1.8.31-1ubuntu1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream sudo package and not the sudo package as distributed by Ubuntu. See How to fix? for Ubuntu:20.04 relevant fixed versions and status.

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

References

CVSS Scores

version 3.1