Microsoft .NET Framework 1.1 SP1, 2.0 SP2, 3.5, 3.5.1, 4, 4.5, and 4.5.1 does not properly determine TCP connection states, which allows remote attackers to cause a denial of service (ASP.NET daemon hang) via crafted HTTP requests that trigger persistent resource consumption for a (1) stale or (2) closed connection, as exploited in the wild in February 2014, aka "POST Request DoS Vulnerability."
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2014/ms14-009
http://www.securitytracker.com/id/1029745
http://www.securityfocus.com/bid/65415