The URL handling in Shell32.dll in the Windows shell in Microsoft Windows XP and Server 2003, with Internet Explorer 7 installed, allows remote attackers to execute arbitrary programs via invalid "%" sequences in a mailto: or other URI handler, as demonstrated using mIRC, Outlook, Firefox, Adobe Reader, Skype, and other applications. NOTE: this issue might be related to other issues involving URL handlers in Windows systems, such as CVE-2007-3845. There also might be separate but closely related issues in the applications that are invoked by the handlers.