Exchange CXP team released a number of Update Rollups for versions of Exchange Server to the Download Center and via Microsoft Update.
Update Rollup 2 for Exchange Server 2010 Service Pack 1
Update Rollup 2 for Exchange Server 2007 Service Pack 3
Update Rollup 5 for Exchange Server 2010 RTM
Update Rollup 5 for Exchange Server 2007 Service Pack 2
Note for Forefront users:
For those of you running Forefront, be sure you perform these important steps from the command line in the Forefront directory before and after this rollup’s installation process. Without these steps, Exchange services for Information Store and Transport will not start back up. You will need to disable ForeFront via “fscutility /disable” before installing the patch and then re-enable after the patch by running “fscutility /enable” to start it up again post installation.