Build App Online <= 1.0.23 - Missing Authorization to Arbitrary Post Author Modification via 'build-app-online-update-vendor-product' AJAX Action

The Build App Online plugin for WordPress is vulnerable to unauthorized access in all versions up to, and including, 1.0.23. This is due to the plugin registering the 'build-app-online-update-vendor-product' AJAX action via wp_ajax_nopriv_ without proper authentication checks, capability verification, or nonce validation in the update_vendor_product() function. The function accepts a user-supplied post ID from the request and calls wp_update_post() to modify the post_author field without validating whether the user has permission to modify the specified post. This makes it possible for unauthenticated attackers to modify the post_author of arbitrary posts to 0 (orphaning posts from their legitimate authors), or for authenticated attackers to claim ownership of any post by setting themselves as the author.