The Simple Page Transition WordPress plugin through 1.4.1 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 when the unfiltered_html capability is disallowed (for example in multisite setup)
https://wpscan.com/vulnerability/4a98a024-1f84-482f-9dc9-4714ac42c094