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.

Mozilla Firefox before 2.0.0.8, Thunderbird before 2.0.0.8, and SeaMonkey before 1.1.5 allows remote attackers to execute arbitrary commands via a (1) mailto, (2) nntp, (3) news, or (4) snews URI with invalid "%" encoding, related to improper file type handling on Windows XP with Internet Explorer 7 installed, a variant of CVE-2007-3845.

Mozilla Firefox before 2.0.0.6, Thunderbird before 1.5.0.13 and 2.x before 2.0.0.6, and SeaMonkey before 1.1.4 allow remote attackers to execute arbitrary commands via certain vectors associated with launching "a file handling program based on the file extension at the end of the URI," a variant of CVE-2007-4041. NOTE: the vendor states that "it is still possible to launch a filetype handler based on extension rather than the registered protocol handler."