The XrayWrapper implementation in Mozilla Firefox before 23.0 and SeaMonkey before 2.20 does not properly address the possibility of an XBL scope bypass resulting from non-native arguments in XBL function calls, which makes it easier for remote attackers to conduct cross-site scripting (XSS) attacks by leveraging access to an unprivileged object.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A18830
https://bugzilla.mozilla.org/show_bug.cgi?id=843829
http://www.mozilla.org/security/announce/2013/mfsa2013-70.html