The Simple Page Access Restriction plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.0.31. This is due to missing nonce validation and capability checks in the settings save handler in the settings.php script. This makes it possible for unauthenticated attackers to (1) enable or disable access protection on all post types or taxonomies, (2) force every new page/post to be public or private, regardless of meta-box settings, (3) cause a silent wipe of all plugin data when it’s later removed, or (4) to conduct URL redirection attacks via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.