RHEL 9 must remove all software components after updated versions have been installed.

Previous versions of software components that are not removed from the information system after updates have been installed may be exploited by some adversaries.

Verify RHEL 9 removes all software components after updated versions have been installed with the following command:

$ sudo grep -i clean_requirements_on_remove /etc/dnf/dnf.conf clean_requirements_on_remove=True

If "clean_requirements_on_remove" is not set to either "1", "true", or "yes" (keywords containing letters are case insensitive), this is a finding.

Configure RHEL 9 to remove all software components after updated versions have been installed.

Edit the file "/etc/dnf/dnf.conf" by adding or editing the following line:

clean_requirements_on_remove=True

Note: Any of the following are acceptable: "1", "true", or "yes" (keywords containing letters are case insensitive).