Uyuni follows a rolling release model, meaning there is no maintenance for a given Uyuni version and all bugfixes are provided by the next version.
However there are some exceptional situations where patches need to be provided, for example for CVEs, and that is what this procedure covers.
1. Add the patches repository to the Server, if you do not have it already:
$ sudo zypper addrepo https://download.opensuse.org/repositories/systemsmanagement:/Uyuni:/Stable:/Patches/openSUSE_Leap_15.2/systemsmanagement:Uyuni:Stable:Patches.repo
2. Refresh the metadata:
$ sudo zypper refresh
3. Stop the services:
$ sudo spacewalk-service stop
4. Apply the update:
$ sudo zypper update
5. Restart the services:
$ sudo spacewalk-service start
1. Sync all the affected client tools repositories
2. Update the clients using the Uyuni Server as you would for any other updates