Severity Rating: Critical - Revision Note: V3.0 (February 22, 2011): Announced a detection change to offer the Microsoft .NET Framework 4.0 update packages to customers who install Microsoft .NET Framework 4.0 after installing Windows 7 for x64-based Systems Service Pack 1, Windows Server 2008 R2 for x64-based Systems Service Pack 1, or Windows Server 2008 R2 for Itanium-based Systems Service Pack 1. Customers who have already successfully updated their systems do not need to take any action.

Summary: This security update resolves a privately reported vulnerability in Microsoft .NET Framework. The vulnerability could allow remote code execution on a client system if a user views a specially crafted Web page using a Web browser that can run XAML Browser Applications (XBAPs). Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights. The vulnerability could also allow remote code execution on a server system running IIS, if that server allows processing ASP.NET pages and an attacker succeeds in uploading a specially crafted ASP.NET page to that server and then executes the page, as could be the case in a Web hosting scenario.

Severity Rating: Important - Revision Note: V4.0 (February 22, 2011): Announced a detection change to offer the Microsoft .NET Framework 4.0 (KB2416472) update packages to customers who install Microsoft .NET Framework 4.0 after installing Windows 7 for 32-bit Systems Service Pack 1, Windows 7 for x64-based Systems Service Pack 1, Windows Server 2008 R2 for x64-based Systems Service Pack 1, or Windows Server 2008 R2 for Itanium-based Systems Service Pack 1. Customers who have already successfully updated their systems do not need to take any action.

Summary: This security update resolves a publicly disclosed vulnerability in ASP.NET. The vulnerability could allow information disclosure. An attacker who successfully exploited this vulnerability could read data, such as the view state, which was encrypted by the server. This vulnerability can also be used for data tampering, which, if successfully exploited, could be used to decrypt and tamper with the data encrypted by the server. Microsoft .NET Framework versions prior to Microsoft .NET Framework 3.5 Service Pack 1 are not affected by the file content disclosure portion of this vulnerability.