The Print, PDF, Email by PrintFriendly WordPress plugin before 5.2.3 does not sanitise and escape the Custom Button Text settings, which could allow high privilege users such as admin to perform cross-Site Scripting attacks even when the unfiltered_html capability is disallowed
https://wpscan.com/vulnerability/b586b217-f91e-42d3-81f1-cc3ee3a4b01e