the Exchange 2010 Rollup8 has a bug in it so Microsoft removed the download link and will replace this rollup. If you happen to be fast and already installed KB2986475, Microsoft recomend to uninstall it and wait for the updatged rollup.Exchange Server 2013 Cumulative Update 7 (CU7) is released.
A version 2 of Exchange 2010 SP3 UR8 is now released, download here.
Exchange 2013 Cumulative Update 7.
Download link and KB2986485
Exchange Server 2010 Service Pack 3, Update Rollup 8.
Download link and KB2986475
Exchange Server 2007 Service Pack 3, Update Rollup 15.
Download link and KB2996150
Notice that there is Active directory schema updates that must be applied before installing Exchange 2013 CU7.