Post Type Switcher <= 4.0.0 - Insecure Direct Object Reference to Authenticated (Author+) Post Type Change

The Post Type Switcher plugin for WordPress is vulnerable to Insecure Direct Object Reference in versions up to, and including, 4.0.0 due to missing validation on a user controlled key. This makes it possible for authenticated attackers, with Author-level access and above, to modify the post type of arbitrary posts and pages they do not own, including those created by administrators, which can lead to site disruption, broken navigation, and SEO impact.