Vulnerability Discussion

User namespaces are used primarily for Linux containers. The value "0" disallows the use of user namespaces.

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