Pre-Publish Checklist <= 1.1.1 - Insecure Direct Object Reference to Arbitrary Post '_ppc_meta_key' Update

The Pre-Publish Checklist plugin for WordPress is vulnerable to Insecure Direct Object Reference in versions up to, and including, 1.1.1 via the ppc_meta_box_ajax_add_handler and ppc_meta_box_ajax_delete_handler functions due to missing validation on a user controlled key. This can allow authenticated attackers with contributor-level access and above to modify and delete the '_ppc_meta_key' post meta value for arbitrary posts.