There is an HTML injection vulnerability in Esri Portal for ArcGIS versions 11.1 and below that may allow a remote, unauthenticated attacker to create a crafted link which when clicked could render arbitrary HTML in the victim’s browser.
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special characters such as "<", ">", and "&" that could be interpreted as web-scripting elements when they are sent to a downstream component that processes web pages.
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.