The WP Attachments WordPress plugin before 5.0.5 does not sanitize and escapes 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/017ca231-e019-4694-afa2-ab7f8481ae63