January Security Patch Can Break SharePoint 2013. Read more>>>
Please be mindful that just applying the security update for SharePoint servers, without the full SharePoint/Project Server CU can cause issues. I would high recommend that user don't enable Automatic Updates on SharePoint Server, but instead, download and install them manually. Be in control of what is being applied to the servers. Not only does a 'bad' patch break SharePoint, it cannot be uninstalled.