The Fluent Forms WordPress plugin before 5.2.1 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup).
https://wpscan.com/vulnerability/a2c56e42-3b3a-4e23-933f-40cf63e222c0/