Microsoft .NET Framework 2.0 SP1 and SP2, 3.5 Gold and SP1, 3.5.1, and 4.0, and Silverlight 4 before 4.0.60531.0, does not properly validate arguments to unspecified networking API functions, which allows remote attackers to execute arbitrary code via (1) a crafted XAML browser application (aka XBAP), (2) a crafted ASP.NET application, (3) a crafted .NET Framework application, or (4) a crafted Silverlight application, aka ".NET Framework Array Offset Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12105
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2011/ms11-039