Adobe Acrobat Reader Plugin before 8.0.0 for the Firefox, Internet Explorer, and Opera web browsers allows remote attackers to force the browser to make unauthorized requests to other web sites via a URL in the (1) FDF, (2) xml, and (3) xfdf AJAX request parameters, following the # (hash) character, aka "Universal CSRF and session riding."
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.