The plugin does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed
Put the following payload in the plugin's settings (/wp-admin/options-general.php?page=th23-social) such as Name, Account and Follow Shortcodes: "><img src=x onerror=prompt(/XSS/)>