The Quiz Maker WordPress plugin before 6.5.9.9 does not sanitize 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/ba6b6b82-6f21-45ff-bd64-685ea8ae1b82/