OL 9 must disable the use of user namespaces.

Severity
Group ID
Group Title
Version
Rule ID
Date
STIG Version
mediumV-271727SRG-OS-000480-GPOS-00227OL09-00-002370SV-271727r1091893_rule2025-05-081
Description
User namespaces are used primarily for Linux containers. The value "0" disallows the use of user namespaces.
ℹ️ Check
Note: User namespaces are used primarily for Linux containers. If containers are in use, this requirement is Not Applicable. Verify that OL 9 disables the use of user namespaces with the following commands: $ sysctl user.max_user_namespaces user.max_user_namespaces = 0 If the returned line does not have a value of "0", or a line is not returned, this is a finding.
✔️ Fix
Configure OL 9 to disable the use of user namespaces by adding the following line to a file, in the "/etc/sysctl.d" directory: Note: User namespaces are used primarily for Linux containers. If containers are in use, this requirement is Not Applicable. user.max_user_namespaces = 0 The system configuration files need to be reloaded for the changes to take effect. To reload the contents of the files, run the following command: $ sudo sysctl --system