Microsoft has published a Microsoft Security Advisory about a security vulnerability in ASP.NET.  This vulnerability exists in all versions of ASP.NET.

 

This vulnerability was publically disclosed late Friday at a security conference.  We recommend that all customers immediately apply a workaround (described below) to prevent attackers from using this vulnerability against your ASP.NET applications.

 

THIS IS SO IMPORTANT FOR YOUR ASP.NET APPLICATIONS. DO NOT MISS IT.

 

Please follow below link and apply all solutions to your applications.

 

http://weblogs.asp.net/scottgu/archive/2010/09/18/important-asp-net-security-vulnerability.aspx