ACF to REST API <= 3.3.4 - Insecure Direct Object Reference to Authenticated (Contributor+) ACF Field/Option Modification

The ACF to REST API plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 3.3.4. This is due to insufficient capability checks in the update_item_permissions_check() method, which only verifies that the current user has the edit_posts capability without checking object-specific permissions (e.g., edit_post($id), edit_user($id), manage_options). This makes it possible for authenticated attackers, with Contributor-level access and above, to modify ACF fields on posts they do not own, any user account, comments, taxonomy terms, and even the global options page via the /wp-json/acf/v3/{type}/{id} endpoints, granted they can authenticate to the site.