The Quick Paypal Payments WordPress plugin before 5.7.26.4 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/0d247a3d-154e-4da7-a147-c1c7e1b5e87e