Please note that there are know issues with this update on Windows 8.1 clients:
Microsoft has released a new update for the System Center Endpoint Protection client.
The update are available from Windows update ad explained here:
Newly deployed clients from Configuration Manager will need this update as well, unless you use the scepinstall.exe in this package, this is because CU4 only includes the October 2014 SCEP update.
Your System Center Configuration Manager 2012 R2 must have Cumulative Update 1 or later installed.
After installation a restart may be required.
Update offered from Windows Update:
This also means that the update is available for Configuration Manager clients:
After updating the client it will report version 18.104.22.168