CVE-2026-4807 Appointment Booking Calendar <= 1.6.10.6 - Unauthenticated Arbitrary Appointment View, Modification and Deletion
Unauthenticated attackers can view, modify, or delete arbitrary appointments by exploiting flawed nonce validation in the Appointment Booking Calendar plugin.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-4807?
CVE-2026-4807 is a medium-severity missing authorization vulnerability in croixhaug Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin, published on 7 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
The Appointment Booking Calendar plugin for WordPress is vulnerable to Missing Authorization in versions up to and including 1.6.10.6. This is due to a flawed authorization logic in the nonce_permissions_check() method combined with the public exposure of a site-wide reusable nonce. The plugin exposes a public_nonce value through the /wp-json/ssa/v1/embed-inner endpoint, which is accessible to unauthenticated users. The appointment deletion endpoint at /wp-json/ssa/v1/appointments/{id}/delete and /wp-json/ssa/v1/appointments/bulk use a permission check that accepts requests containing both an X-WP-Nonce header (with any arbitrary value) and an X-PUBLIC-Nonce header (with the valid public nonce). When the X-WP-Nonce validation fails, the function falls back to validating the X-PUBLIC-Nonce without properly rejecting the request. Since the public_nonce is exposed to all unauthenticated visitors and is site-wide (not user-specific or appointment-specific), attackers can obtain it and use it to view details of arbitrary appointments, including the public_edit_url, or delete arbitrary appointments by ID. This makes it possible for unauthenticated attackers to view, delete or modify any appointment in the system, disclosing sensitive appointment data, causing service disruption, and loss of booking records.
Weakness: CWE-862
Which versions are affected by CVE-2026-4807?
How do I fix CVE-2026-4807?
No fix has been published for CVE-2026-4807 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-4807 being exploited?
There is no known exploitation of CVE-2026-4807 in the wild and no public exploit code.
Sources
Also known as GHSA-x96p-55v7-jmrq.