Yesterday, we informed you that Microsoft released a security update that addresses the ASP.NET Security Vulnerability via Microsoft Download Center. However, if you download updates directly, then you need to manually select and download appropriate updates. Below is a table of all of the different update packages available via MDC. The downloads are split up by Windows OS (and corresponding service pack and processor architecture). Each OS version bucket below includes a listing of all available versions of .NET supported on it, and includes KB and download links to appropriate security updates.
Download and apply the update packages for each version of .NET that you're using on that server: