The Booking for Appointments and Events Calendar – Amelia (Premium) plugin for WordPress is vulnerable to Privilege Escalation in versions 8.0 - 9.6.2. This is due to insufficient validation of the attacker-controlled 'type' parameter in the customer update endpoint, which allows customers to set their role to 'manager' and trigger creation of a WordPress user with the wpamelia-manager role when the 'externalId' parameter is set to 0. This makes it possible for unauthenticated attackers to escalate their privileges to administrator by first elevating to the manager role, then creating a provider entity linked to an administrator user ID and overwriting that administrator's password.

The Amelia Premium plugin for WordPress contains a critical privilege escalation vulnerability affecting versions 8.0 through 9.6.2. The flaw stems from insufficient validation of the attacker-controlled 'type' parameter in the customer update endpoint. An unauthenticated attacker can exploit this by first elevating their role to 'manager' by manipulating the 'type' parameter, then setting the 'externalId' parameter to 0 to trigger creation of a WordPress user with the wpamelia-manager role. Subsequently, the attacker can create a provider entity linked to an administrator user ID and overwrite that administrator's password. This multi-step attack chain ultimately allows full administrator-level access to the WordPress site. The vulnerability poses a significant risk to any WordPress site running the affected versions of the Amelia Premium booking plugin.