Microsoft has released Cumulative Update 5 for Exchange Server 2013.
From the Microsoft Exchange Team blog:
Cumulative Update 5 represents the continuation of our Exchange Server 2013 servicing and builds upon Exchange Server 2013 Service Pack 1. The release includes fixes for customer reported issues, minor product enhancements and previously released security bulletins. A complete list of customer reported issues resolved in Exchange Server 2013 Cumulative Update 5 can be found in Knowledge Base Article KB2936880. Customers running any previous release of Exchange Server 2013 can move directly to Cumulative Update 5 today. Customers deploying Exchange Server 2013 for the first time may skip previous releases and start their deployment with Cumulative Update 5 as well.
CU5 delivers improvements to OAB management for large/distributed environments, which Microsoft has detailed in a blog post here.
Important Note: Cumulative Update 5 includes a Managed Availability probe configuration that is frequently restarting the Microsoft Exchange Shared Cache Service in some environments. The service is being added to provide future performance improvements and is not used in Cumulative Update 5. More information is available in KB2971467.
Also includes is the fix for the “Some or all identity references could not be translated” error in Exchange 2013 SP1.
Cumulative Update 5 is available for download here.
For deployment steps refer to this guide to installing cumulative updates for Exchange Server 2013.