Open redirect vulnerability in the Forms Authentication feature in the ASP.NET subsystem in Microsoft .NET Framework 2.0 SP2, 3.5 SP1, 3.5.1, and 4.0 allows remote attackers to redirect users to arbitrary web sites and conduct phishing attacks via a crafted return URL, aka "Insecure Redirect in .NET Form Authentication Vulnerability."
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.