Mozilla Firefox 3.0.x before 3.0.18 and 3.5.x before 3.5.8, and SeaMonkey before 2.0.3, does not properly support the application/octet-stream content type as a protection mechanism against execution of web script in certain circumstances involving SVG and the EMBED element, which allows remote attackers to bypass the Same Origin Policy and conduct cross-site scripting (XSS) attacks via an embedded SVG document.