December 2014 CU is a full server package – meaning no other update is required to fully patch SharePoint to this level.
Prereq’s: SharePoint Server 2013 SP1 or March 2013 PU for SharePoint 2013.
The KB articles links for December CU:
KB 2910945 – SharePoint Foundation 2013
KB 2910938 – SharePoint Server 2013 (includes SharePoint Foundation CU)
KB 2910911 – SharePoint Server 2013 with Project Server (includes SharePoint Foundation CU, SharePoint Server CU & Project Server CU)
KB 2899574 – Office Web Apps Server 2013
Full Server Package download links:
Download SharePoint Foundation 2013 December 2014 CU
Download SharePoint Server 2013 December 2014 CU
Download Project Server 2013 December 2014 CU
Download Office Web Apps Server 2013 December 2014 CU
Note: SharePoint 2013 Configuration Wizard need to be run on all SharePoint machines after installing the binaries in all machines starting with machine hosting Central Admin.
For Additional information please follow this blog http://blogs.technet.com/b/stefan_gossner/archive/2014/12/09/december-2014-cu-for-sharepoint-2013-has-been-released.aspx by Stefan Gossner.