Secunia

Some vulnerabilities have been reported in Microsoft .NET Framework, which can be exploited by malicious people to compromise a vulnerable system.

1) An unspecified error can be exploited to obtain a managed pointer to stack memory, which can be exploited to execute arbitrary code e.g. via a specially crafted ASP .NET application, or XBAP (XAML browser application).

2) An error in the verification of Microsoft .NET verifiable code can be exploited to bypass a type equality check and execute arbitrary code e.g. via a specially crafted ASP .NET application or XBAP.

3) An error exists in the Microsoft .NET Common Language Runtime (CLR) in the handling of interfaces. This can be exploited to corrupt memory and execute arbitrary code e.g. via a specially crafted ASP .NET application or XBAP.

Solution
Apply patches.
Further details available in Customer Area

Provided and/or discovered by
1) The vendor credits Pavel Minaev.
2) The vendor credits Jeroen Frijters of Sumatra.

Original Advisory
MS09-061 (KB974378, KB953297, KB953300, KB974417, KB953295, KB953298, KB974468, KB974292, KB974467, KB974291, KB974469, KB974470):
http://www.microsoft.com/technet/security/bulletin/MS09-061.mspx

Deep Links
Links available in Customer Area