Cross-site scripting (XSS) vulnerability in Plupload.as in Moxiecode plupload before 1.5.5, as used in WordPress before 3.5.1 and other products, allows remote attackers to inject arbitrary web script or HTML via the id parameter.
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.