Microsoft has re-released the latest update rollups for Exchange 2010 & 2007.
These updates address an issue in which digital signatures on files produced and signed by Microsoft will expire prematurely, as described in Microsoft Security Advisory 2749655.
Update Rollup 4-v2 for Exchange Server 2010 Service Pack 2 (KB2756485)
Update Rollup 7-v2 for Exchange Server 2010 Service Pack 1 (KB2756496)
Update Rollup 8-v2 for Exchange Server 2007 Service Pack 3 (KB2756497)
You don’t have to uninstall the existing rollup (v1) in order to install the new ones.