Puppet Platform 5.5.4 is a bug-fix and feature release that includes updates for Puppet 5.5.3, Facter 3.11.3, and pxp-agent 1.9.3. It also adds Puppet agent packages for Fedora 28 and deprecates MCollective. For details, see the puppet-agent release notes.
PuppetDB 5.2.4 is a minor bug-fix release, and Puppet Server 5.3.4 adds packages for Ubuntu 18.04 (Bionic Beaver). For details, see PuppetDB and Puppet Server release notes.