wappointment Appointment Bookings for Zoom GoogleMeet and more Plugin REST Endpoint tryCancel authorization

Summaryinfo

A vulnerability identified as critical has been detected in wappointment Appointment Bookings for Zoom GoogleMeet and more Plugin up to 2.7.6 on WordPress. The impacted element is the function tryCancel of the component REST Endpoint. This manipulation of the argument appointmentkey causes authorization. This vulnerability is handled as CVE-2026-9188. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in wappointment Appointment Bookings for Zoom GoogleMeet and more Plugin up to 2.7.6 on WordPress. It has been declared as critical. Affected by this vulnerability is the function tryCancel of the component REST Endpoint. The manipulation of the argument appointmentkey with an unknown input leads to a authorization vulnerability. The CWE definition for the vulnerability is CWE-639. The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The weakness was released by davidfdzmorilla. It is possible to read the advisory at wordfence.com. This vulnerability is known as CVE-2026-9188 since 05/21/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 2.7.5 eliminates this vulnerability.

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Productinfo

Type

• Appointment Software

Vendor

• wappointment

Name

• Appointment Bookings for Zoom GoogleMeet and more Plugin

Version

• 2.7.0
• 2.7.1
• 2.7.2
• 2.7.3
• 2.7.4
• 2.7.5
• 2.7.6

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

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