If you plan to deploy this cumulative update on an AlwaysOn configuration, you must read the following Knowledge Base article before you do this:
AlwaysOn availability groups reported as NOT SYNCHRONIZING after you apply SQL Server 2014 CU5, SQL Server 2012 SP2 CU4, or SQL Server 2012 SP2 CU3
This article describes cumulative update package 3 (Build number: 11.0.5556.0) for Microsoft SQL Server 2012 Service Pack 2 (SP2). This update contains hotfixes for issues that were fixed after the release of SQL Server 2012 SP2.
How to obtain this cumulative update package
Click "Hotfix Download Available" at the top of this Microsoft Knowledge Base article. If the "Hotfix Request" page doesn't appear, contact Microsoft Customer Service and Support to obtain the cumulative update package.