Microsoft SharePoint Server 2013 SP1 and SharePoint Foundation 2013 SP1 allow remote authenticated users to bypass intended Access Control Policy restrictions and conduct cross-site scripting (XSS) attacks by modifying a webpart, aka "Microsoft SharePoint Security Feature Bypass," a different vulnerability than CVE-2015-6117.
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2016/ms16-004