An attacker submitting facts to the Foreman server containing HTML can cause a stored XSS on certain pages: (1) Facts page, when clicking on the "chart" button and hovering over the chart; (2) Trends page, when checking the graph for a trend based on a such fact; (3) Statistics page, for facts that are aggregated on this page.
https://github.com/theforeman/foreman/pull/4967