The Web Proxy Auto-Discovery (WPAD) functionality in Microsoft .NET Framework 2.0 SP2, 3.5, 3.5.1, 4, and 4.5 does not validate configuration data that is returned during acquisition of proxy settings, which allows remote attackers to execute arbitrary JavaScript code by providing crafted data during execution of (1) an XAML browser application (aka XBAP) or (2) a .NET Framework application, aka "Web Proxy Auto-Discovery Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A15810
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2012/ms12-074
http://www.us-cert.gov/cas/techalerts/TA12-318A.html
http://www.securitytracker.com/id?1027753
http://www.securityfocus.com/bid/56463