Contest Gallery <= 30.0.2 - Authenticated (Author+) Privilege Escalation via 'RegistryUserRole' Parameter

Summary

The Contest Gallery – Upload & Vote Photos, Media, Sell with PayPal & Stripe plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 30.0.2 via the `RegistryUserRole` parameter. This is due to the plugin's admin menu being registered at the `edit_posts` capability level — granting Contributor-level users access to the plugin's admin pages and a valid `cg_admin` nonce — while the option-saving handler in `change-options-and-sizes.php` performs no `current_user_can()` capability check beyond `check_admin_referer('cg_admin')`, and the `RegistryUserRole` value is processed only through `sanitize_text_field()` and `htmlentities()` without restriction to an allowlist of permitted role names. This makes it possible for authenticated attackers, with author-level access and above, to overwrite the plugin's stored `RegistryUserRole` option with `administrator`, which the `cg_create_wp_user_from_google_user` function then reads back from the `contest_gal1ery_registry_and_login_options` database table without any allowlist validation and passes directly to `wp_update_user()`, effectively promoting a newly registered Google sign-in account to Administrator.