What were you trying to do that didn't work?

Trying to list all the available and installed security update using

1. dnf updateinfo --list --security --all

This command won't list the security update of packages which are not installed. Only shows data wrt packages installed on the system

For example:
Let's say `apr` package is not at all installed in the system, even if you run above command it wont list the security update for thos package.

Whereas in RHEL 7

# yum updateinfo list security all

It lists all the security update of packages of all installed and not installed packages.