Microsoft has released SQL Server 2012 Service Pack 3 CU3, which is Build 11.0.6537. There are 23 hotfixes in the public fix list, some of which look pretty significant. If you are running SQL Server 2012, you should be on the SP3 branch by now (or at least be planning on doing so soon).
Microsoft also released SQL Server 2012 Service Pack 2 CU12, which is Build 11.0.5649. There are 8 hotfixes in the public fix list.
As you may be aware, Microsoft has changed their official stance about proactively installing Cumulative Updates, as explained in this post:
This means that you should make a greater effort to try to stay as current as possible on Cumulative Updates, despite the extra effort that requires.
If you are still on the SQL Server 2012 RTM or SP1 branches, you are on an “unsupported service pack”, which is not a good place to be, for a number of reasons.