CVE-2026-9188
MediumCVSS 5.3Exploitation Probability (EPSS)
Low risk21th percentile — higher than 21% of all known CVEs
Summary
The Wappointment plugin for WordPress up to version 2.7.6 contains an Insecure Direct Object Reference (IDOR) vulnerability. The authorization key `edit_key` is generated as a predictable, unsalted MD5 hash of a sequential client ID, a publicly observable timestamp, and a small staff ID, allowing unauthenticated attackers to compute it and cancel or reschedule other users' appointments.
Risk Assessment
The organization is at risk of unauthorized appointment cancellations or rescheduling by attackers, leading to scheduling chaos, loss of customer trust, and potential financial losses. The vulnerability is easily exploitable if the cancellation or rescheduling options are enabled.
Recommendation
Immediately update the Wappointment plugin to the latest available version that fixes this vulnerability. Until the update is applied, disable the `allow_cancellation` and `allow_rescheduling` options in the plugin settings.
Original NVD description (English source)
The Appointment Bookings for Zoom GoogleMeet and more – Wappointment plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to and including 2.7.6 via the `appointmentkey` parameter due to the appointment `edit_key` — the sole authorization token consumed by `tryCancel()` — being generated as a predictable, unsalted MD5 hash of only `client_id` (a sequential integer), `start_at` (a publicly observable appointment timestamp), and `staff_id` (a small enumerable integer), with no secret salt or random component, and the unauthenticated cancellation and rescheduling REST endpoints performing no ownership or identity verification beyond matching this reconstructible key. This makes it possible for unauthenticated attackers to compute valid `edit_key` values for appointments belonging to other users and cancel or reschedule those appointments arbitrarily. Exploitation requires the `allow_cancellation` or `allow_rescheduling` setting to be enabled on the site, both of which are common configurations for active booking deployments; an attacker can obtain the inputs needed to reconstruct a victim's key by booking their own appointment to observe their sequential `client_id` and correlating publicly visible appointment times and enumerable staff identifiers.