How to limit updates a specific version of Red Hat Enterprise Linux?

Set a limit on the OS version that can be updated.

# subscription-manager release --show
   Release not set

# subscription-manager release --set=7.2
   Release set to: 7.2
# yum clean all

# subscription-manager release --show
   Release: 7.2

Release the limitation on the OS version that can be updated.

# subscription-manager release --unset
   Release preference has been unset

Delete any cached metadata after setting the release so that your system does not attempt to use any cached metadata.

RHEL 7 and below
# rm -rf /var/cache/yum

RHEL 8
# rm -rf /var/cache/dnf

Reff : https://access.redhat.com/solutions/2761031