Microsoft Windows 2000 Advanced Server

From Microsoft:

The Microsoft Data Access Component Internet Publishing Provider provides access to WebDAV resources over the Internet. By design, it should differentiate between requests made by a user and those made by script running in the users browser. However, because of an implementation flaw, it handles all requests in the security context of the user. As a result, if a user browsed to a web page or opened an HTML e-mail that contained script, that script could access web-based resources as the user.