Microsoft released Cumulative Update 6 for Exchange Server 2013. You can download from here...

This Cumulative Update comes with several and some of the important fixes. Some of those are...

• Blank page after you sign in to Exchange Server 2013 EAC (formerly ECP)
• OAB generation fails if FIPS is used in an Exchange Server 2013 environment
• You cannot access the archive mailbox of a delegated user after enabling MAPI over HTTP
• Exchange Server 2010 public folder replication fails in an Exchange Server 2013 environment
• Duplicate mailbox folders after migration to Exchange Server 2013