There is a Cross-site Scripting vulnerability in Portal for ArcGIS in versions 11.0 and below that may allow a remote, authenticated attacker to create a crafted link which when accessing the page editor an image will render in the victim’s browser. The privileges required to execute this attack are high.
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.