The Booking Calendar plugin for WordPress is vulnerable to Privilege Escalation in all versions...

The Booking Calendar plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 11.8.2 via the wpbc_ajax_option_save AJAX action. The vulnerability exists because the handle_ajax_save() function applies per-option safeguards only to names explicitly registered via register_option_policy(), causing get_option_policy() to return an empty policy — bypassing all can_save, force_mode, and allowed_keys checks — for any unregistered option name, including core WordPress options, while an attacker-controlled data_name parameter passes through sanitize_key() and is written directly to update_option() without restriction. This makes it possible for authenticated attackers with Editor-level access and above to escalate their privileges to Administrator by writing core WordPress options such as default_role=administrator and users_can_register=1, then self-registering a new Administrator account. The nonce check does not meaningfully restrict this attack, as both the nonce value and nonce action are attacker-supplied POST parameters, and a valid nonce is trivially obtainable via admin-ajax.php?action=rest-nonce.