PageLayer < 1.7.7 - Unauthenticated Stored XSS

# Unauthenticated attacker Proof of Concept

1) As a legitimate administrator, schedule a post to be published in a few minutes. 

2) Close every window to that site (to prevent accidentally publishing the post!), and wait for the scheduled time to pass. You may need to schedule it for an hour in the future.

3) Once the scheduled time has passed, ping the site using the following command:

curl --url 'http://vulnerable.site/wp-cron.php?is_pagelayer_editor=1&pagelayer_header_code=</textarea><script>alert(1);</script>'


# Contributor Proof of Concept
- As a user with Contributor capabilities, create a new post draft
- Save it, then edit it using the PageLayer page builder
- Navigate to the "Advanced" tab, and then the " Header, Body and Footer" section
- Enter `</textarea><script>alert(1);</script>` in the Header, Body and Footer code text areas, and save. 
- Preview the resulting post should make the alert prompts go off.