The plugin does not sanitize and escape some of its settings, which could allow high-privilege users such as admin to perform Stored Cross-Site Scripting (XSS) attacks even when the unfiltered_html capability is disallowed (for example, in multisite setup).
Proof of Concept
Put the following payload in any of the plugin’s settings (e.g “Name of Service”) and save:
"><script>alert(/XSS/);</script>