CVE 2013-1692
Mozilla Firefox before 22.0, Firefox ESR 17.x before 17.0.7, Thunderbird before 17.0.7, and Thunderbird ESR 17.x before 17.0.7 do not prevent the inclusion of body data in an XMLHttpRequest HEAD request, which makes it easier for remote attackers to conduct cross-site request forgery (CSRF) attacks via a crafted web site.
See the 
CVE page on Mitre.org
for more details.
