The Mihdan: No External Links WordPress plugin before 5.0.2 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/bf476a3e-05ba-4b54-8a65-3d261ad5337b