The reflection implementation in Microsoft .NET Framework 1.0 SP3, 1.1 SP1, 2.0 SP2, 3.5.1, and 4 does not properly enforce object permissions, which allows remote attackers to execute arbitrary code via (1) a crafted XAML browser application (aka XBAP) or (2) a crafted .NET Framework application, aka "Reflection Bypass Vulnerability."