Collecting security informations only from repo

I have computers runing on redhat on a local network (without any Internet connection of course) and I need to know to which CVE they are vulnerable.
Using the "yum-plugin-security --cve" command.
As there is no connection to the Internet I don't have results, although I should have some.

Is it possible to make a clone of the part of the Red Hat repository managing security updates ?

Do you have any clue ? Can't find anything.

Thanks