This indicates an attack attempt against a stack corruption vulnerability in Microsoft .NET Framework.
This vulnerability is caused when the x86 JIT compiler within the .NET Framework incorrectly compiles certain types of function calls. An attacker who successfully exploits this vulnerability could take complete control of an affected system.
Microsoft .NET Framework 2.0 Service Pack 2
Microsoft .NET Framework 3.5 Service Pack 1
Microsoft .NET Framework 3.5.1
Microsoft .NET Framework 4.0
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the patch supplied by the vendor: