SQL Server 2012 SP1 CU4 was released on May 31, 2013. You can get more information from the KB listed below.
2839806 Cumulative update package 4 for SQL Server 2012 SP1
At mean time, the following SQL Server 2012 hotfix got released
2840614 FIX: Master Data Explorer pane does not display in the SQL Server 2012 MDS Add-in for Excel
2840658 FIX: "You have requested to validate more than 10000 members" error when you validate entities in Excel
For more information on SQL CU version, please refer to the following link: