moxieplayer.as in Moxiecode moxieplayer, as used in the TinyMCE Media plugin in WordPress before 3.5.2 and other products, does not consider the presence of a # (pound sign) character during extraction of the QUERY_STRING, which allows remote attackers to pass arbitrary parameters to a Flash application, and conduct content-spoofing attacks, via a crafted string after a ? (question mark) character.
https://bugzilla.redhat.com/show_bug.cgi?id=976784
http://www.debian.org/security/2013/dsa-2718