Note that clients can get information about errata from repodata. As an end user of RHUI, just like an end user of RHSM, you can run the following command at any time:

# yum updateinfo info

The help message also says:

Updateinfo command-specific options:
  --available           advisories about newer versions of installed packages
                        (default)
  --installed           advisories about equal and older versions of installed
                        packages
  --updates             advisories about newer versions of those installed
                        packages for which a newer version is available
  --all                 advisories about any versions of installed packages
  --summary             show summary of advisories (default)
  --list                show list of advisories
  --info                show info of advisories
  --with-cve            show only advisories with CVE reference
  --with-bz             show only advisories with bugzilla reference

  SPEC                  Package specification

This is something that needs to be handled by following the attached knowledge base article - https://access.redhat.com/solutions/7025884