Exchange 2013 CU11 was released on 12/10/2015. CU11 does not contain any schema updates but may contain new RBAC definitions.
Remember, you can install Exchange 2013 from the CU Rollup itself, saving time (CU12 rollup links above).
Noteworthy issues resolved in CU11:
- After applying CU8 you may experience a large IOPS write increase for FolderUpdateGroup on your storage. This issue leads to email delivery delays to the mailbox database.