Ad Inserter < 2.8.17 - Insecure Direct Object Reference to Authenticated (Contributor+) Arbitrary Post Content Disclosure via 'data' Shortcode Attribute

Description

The Ad Inserter – Ad Manager & AdSense Ads plugin for WordPress is vulnerable to Insecure Direct Object Reference in versions up to and including 2.8.16 via the 'data' attribute of the [adinserter] shortcode. This is due to the replace_ai_tags() function processing a {reusable-block-N} tag pattern that calls get_post_field('post_content', N) without verifying the requesting user's capability with current_user_can('read_post'), without restricting the post type to 'wp_block', and without checking the post status. This makes it possible for authenticated attackers, with Contributor-level access and above, to read the full content of arbitrary posts including Private, Draft, Pending, Trashed, and password-protected posts owned by other users, by placing the shortcode in a post they own and previewing it.