This update resolves the "Virtualized UNC Share" security vulnerability found in Microsoft Internet Information Server (IIS) and some of its related software, and is discussed in Microsoft Security Bulletin MS00-019. Install this update to prevent the source code of certain types of files to be sent from a Web server to a visiting user's browser. The vulnerability does not enable unauthorized users to change files or take administrative action on the Web server.
This vulnerability only occurs under very specific, and fairly unusual conditions. For more information, read Microsoft Security Bulletin MS00-019. (This site may be in English.)