The Donations via PayPal WordPress plugin before 1.9.9 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/48ec2e4a-0190-4f36-afd1-d5799ba28c13