A Cross Site Scripting (XSS) vulnerability in Concrete CMS v.9.2.1 allows an attacker to execute arbitrary code via a crafted script to the SEO - Extra from Page Settings. NOTE: the vendor disputes this because this SEO-related header change can only be made by an admin, and allowing an admin to place JavaScript there is an intentional customization feature.
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.