Are SharePoint 2013 Cumulative Updates available through WSUS, and if so, which Product Classifications should be selected?
it is highly recommended dont install the SharePoint cu via windows update as SharePoint updates required more work after installation of CU.
For SharePoint installation, you have to Install the SharePoint CU then followed by a Config Wizard on each server of the farm. which required a down time.
So please plan it accordingly.
Never use automated patch management for SharePoint updates. Each update requires manual intervention. In addition, SharePoint 2013 patches take an especially lengthy time to install if you do not stop specific services before hand. Binary installation does take services offline during specific periods within the installation. As does the Config Wizard which you must run post-deployment on all servers in the farm.
Public Updates are available through WSUS, however. Cumulative Updates are not.