Microsoft Windows Explorer for Windows XP has been reported to be prone to a remote denial of service vulnerability. This issue is due to a failure of the application to properly validate user-supplied input via the 'shell:' command. The 'shell:' command is a parameter that a user can specify when including a URI in an HTML tag. This command allows the HTML script to potentially execute any program specified after the 'shell:' command. Successful exploitation of this issue would cause the affected application to crash, denying service to legitimate users. The issue may be triggered when a user follows an HTML link formatted like so: <a href=shell:windowssystem32calc.exe>link</a> or when a user views an HTML document containing the following tag: <iframe src=shell:windowssystem32calc.exe></iframe>