The serialization functionality in Microsoft .NET Framework 2.0 SP2, 3.5, 3.5 SP1, 3.5.1, 4, and 4.5 does not properly check the permissions of delegate objects, which allows remote attackers to execute arbitrary code via (1) a crafted XAML browser application (XBAP) or (2) a crafted .NET Framework application that leverages a partial-trust relationship, aka "Delegate Serialization Vulnerability."