We recently announced on the Microsoft Update Product Team Blog a set of changes made to the Windows Update Agent. In an effort to provide additional protection for our WSUS customers, we are releasing an update that enhances the security of Windows Update, the Microsoft Update (WU/MU) Client, and Windows Server Update Services. The update applies to WSUS 3.0 SP2, as well as the WSUS role running on Windows Server 2012 and Windows Server 2012 R2.
Improvements include further hardening of the infrastructure used by WU/MU client and the communication channel between WU/MU Client and Service. Additionally, the communication channel between WSUS and WU/MU service has been hardened. This update to WSUS also rolls up all prior updates.
Details on the changes to the WU/MU client can be found at KB 2887535.
Details and additional considerations, and download links, for the update to WSUS can be found at KB 2938066.