The Meta Box plugin for WordPress is vulnerable to arbitrary file deletion due to insufficient file path validation in the 'ajax_delete_file' function in all versions up to, and including, 5.11.1. This makes it possible for authenticated attackers, with Contributor-level access and above, to delete arbitrary files on the server, which can easily lead to remote code execution when the right file is deleted (such as wp-config.php).

The Meta Box WordPress plugin before 5.9.4 does not prevent users with at least the contributor role from access arbitrary custom fields assigned to other user's posts.

The Meta Box – WordPress Custom Fields Framework plugin for WordPress is vulnerable to Stored Cross-Site Scripting via custom post meta values displayed through the plugin's shortcode in all versions up to, and including, 5.9.2 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.