On August 25, 2016, Microsoft released SQL Server 2014 Service Pack 2 CU1, which is build 12.0.5511.0. This cumulative update has 45 hotfixes in the public fix list. If you are running SQL Server 2014, this is the branch and build that you should try to be on as soon as you can do your testing and planning (since it is the “latest and greatest” SP and CU).
Currently, the SP1 and SP2 branches are not chronologically aligned as far as release dates go, but that is supposed to be fixed when SP1 CU9 and SP2 CU2 are released at the same time in October.