Microsoft is investigating reports of a vulnerability in VBScript that is exposed on supported versions of Microsoft Windows 2000, Windows XP, and Windows Server 2003 through the use of Internet Explorer. Our investigation has shown that the vulnerability cannot be exploited on Windows 7, Windows Server 2008 R2, Windows Vista, or Windows Server 2008. The main impact of the vulnerability is remote code execution. We are not aware of attacks that try to use the reported vulnerabilities or of customer impact at this time.The vulnerability exists in the way that VBScript interacts with Windows Help files when using Internet Explorer. If a malicious Web site displayed a specially crafted dialog box and a user pressed the <F1> key, arbitrary code could be executed in the security context of the currently logged-on user. On systems running Windows Server 2003, Internet Explorer Enhanced Security Configuration is enabled by default, which helps to mitigate against this issue.Upon completion of this investigation, Microsoft will take the appropriate action to help protect our customers. This may include providing a security update through our monthly release process or providing an out-of-cycle security update, depending on customer needs.