The plugin 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)
1. Fields in the "Options" section of the plugin are vulnerable to XSS. For example, the "Button Text" field is affected by the payload: `<script>alert('XSS')</script>`
2. Reload page to see XSS.