As part of their Incremental Service Modelling, Microsoft have released SQL Server 2014 Cumulative Update #2 for SQL Server 2014 SP1.
To apply this cumulative update package, you must be running SQL Server 2014 SP1. So it is pertinent for versions 12.0.4100.1
The build number of the cumulative update package is 12.0.4422.0. You may have to restart the computer after you apply this cumulative update package. The cumulative update package updates only those components currently installed.
This update contains 44 updates. As usual, make sure you deploy Cumulative Updates in test environments before deploying straight to production and that you apply the most recent build that you apply the most recent build.