Buffer overflow in various Microsoft applications for Macintosh allows remote attackers to cause a denial of service (crash) or execute arbitrary code by invoking the file:// directive with a large number of / characters, which affects Internet Explorer 5.1, Outlook Express 5.0 through 5.0.2, Entourage v. X and 2001, PowerPoint v. X, 2001, and 98, and Excel v. X and 2001 for Macintosh.