Mozilla Firefox before 3.5.16 and 3.6.x before 3.6.13, and SeaMonkey before 2.0.11, when the XMLHttpRequestSpy module in the Firebug add-on is used, does not properly handle interaction between the XMLHttpRequestSpy object and chrome privileged objects, which allows remote attackers to execute arbitrary JavaScript via a crafted HTTP response.  NOTE: this vulnerability exists because of an incomplete fix for CVE-2010-0179.