Mozilla Firefox before 3.5.14 and 3.6.x before 3.6.11, Thunderbird before 3.0.9 and 3.1.x before 3.1.5, and SeaMonkey before 2.0.9 do not properly handle certain modal calls made by javascript: URLs in circumstances related to opening a new window and performing cross-domain navigation, which allows remote attackers to bypass the Same Origin Policy via a crafted HTML document.