You might see that your WSUS server will crash after KB3159706 is installed.
The event log will report event ID 507 Update Services failed its initialization and stopped.
In the support article you will se that manual intervention is required, but since the update is pushed from Windows Update and WSUS itself, you might not be aware of the change.
Manual steps required to complete the installation of this update
Open an elevated Command Prompt window, and then run the following command (case sensitive, assume “C” as the system volume):
“C:Program FilesUpdate ServicesToolswsusutil.exe” postinstall /servicing
Select HTTP Activation under .NET Framework 4.5 Features in the Server Manager Add Roles and Features wizard (if not already installed).
Restart the WSUS service.
If SSL is enabled on the WSUS server you need to do a few more changes as explained in the support article KB3159706
And as always remember proper maintenance on the server:
Software update maintenance in System Center 2012 Configuration Manager