XMLHttpRequest 302 response disclosure — Mozilla

Marius Schilder of Google Security reported that when a XMLHttpRequest is made to a same-origin resource which 302 redirects to a resource in a different domain, the response from the cross-domain resource is readable by the site issuing the XHR. Cookies marked HttpOnly were not readable, but other potentially sensitive data could be revealed in the XHR response including URL parameters and content in the response body.