OpenReception's appointment booking software provides an end-to-end encrypted appointment booking platform. Prior to version 2.2.2, an attacker overbooks an agent, placing multiple appointments into a single time slot that the system is designed to keep exclusive. The number of overlapping appointments equals the number of concurrent requests, and one booking token is enough because the token is consumed after the insert. This results in the integrity of the booking-calendar breaking and availability being denied to other clients. This issue has been patched in version 2.2.2.