CVE-2026-109369: WP Booking System <= 2.1.0.3 - Missing Authorization to Authenticated (Subscriber+) Privilege Escalation via 'user_permission' Parameter via Cross-Form Nonce Reuse
The WP Booking System – Booking Calendar plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 2.1.0.3 This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for authenticated attackers, with subscriber-level access and above, to grant themselves and arbitrary other users edit access to every booking form on the site by overwriting the userpermission meta that governs the plugin's own access-control list. Exploitation requires the attacker to have already been delegated edit rights on at least one booking form, as this delegation both downgrades the submenu capability to 'read' (making the edit page accessible) and allows them to harvest a valid wpbseditform nonce that will pass validation against any other formid.
Affected Software
Event History
Frequently Asked Questions
Which users can realistically exploit this issue?
An attacker must be authenticated and have subscriber-level access or higher, but they must also already have edit rights on at least one booking form. A subscriber without delegated edit access to any booking form cannot meet the stated exploitation prerequisites.
What does an attacker need to do to exploit the authorization bypass?
The attacker needs access to the edit page for a booking form they are already allowed to edit, where they can obtain a valid wpbs_edit_form nonce. They can then reuse that nonce with another form_id and overwrite the user_permission metadata for other booking forms.
What is the impact if exploitation succeeds?
An attacker can grant themselves or other arbitrary users edit access to every booking form on the site. The issue affects the plugin's own booking-form access-control list; no broader WordPress administrative privilege escalation is stated.
How can administrators determine whether their site is exposed to practical exploitation?
Sites using WP Booking System Booking Calendar version 2.1.0.3 or earlier are affected. Practical exposure exists where a low-privileged authenticated user has been delegated edit rights to at least one booking form.