Mozilla: Continued access to initial origin after setting document.domain can lead to XSS attacks (MFSA 2012-76)
Mozilla Firefox before 16.0, Thunderbird before 16.0, and SeaMonkey before 2.13 do not properly implement the HTML5 Same Origin Policy, which allows remote attackers to conduct cross-site scripting (XSS) attacks by leveraging initial-origin access after document.domain has been set.