Published: May 27, 2026 | Last Modified: May 27, 2026
The Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin plugin for WordPress is vulnerable to denial of service in all versions up to, and including, 1.6.11.5. This is due to a publicly accessible REST API endpoint (/wp-json/ssa/v1/async) that calls PHP's sleep() function on a user-supplied delay parameter without any rate limiting. This makes it possible for unauthenticated attackers to exhaust PHP worker processes, denying access to the site to legitimate users.
This analysis is generated by Ghostwire from NVD, CISA KEV, EPSS, and open-source intelligence data. Verify findings through primary sources before acting.