For GOS 4.2 a new patch level is available:
http://www.greenbone.net/en/roadmap-lifecycle/
This update primarily opens GSM ONE to upgrade to GOS 4.3 via the release switch. Please make sure you upgrade first to 4.2.21, reboot, and only then execute the release switch. As always we recommend to create a backup clone before switching the release.
The upgrade from GOS 4.2 to 4.3 is seamless and almost as simple as a patch level upgrade. The upgrade process can take up-to 20 minutes.
Another noteworthy change is the maintenance update of the underlying base system that includes a maintenance update of the database management system.
In total the patch level covers 3 improvements.