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."