CVE-2026-9188: CWE-639 Authorization Bypass Through User-Controlled Key in wappointment Appointment Bookings for Zoom GoogleMeet and more – Wappointment
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.
AI Analysis
Technical Summary
CVE-2026-9188 describes an insecure direct object reference vulnerability in the Wappointment plugin for WordPress. The plugin uses an edit key for appointment authorization, generated as a predictable, unsalted MD5 hash of client_id (sequential integer), start_at (public timestamp), and staff_id (small enumerable integer). Because the key is predictable and no additional ownership or identity verification is performed, unauthenticated attackers can compute valid keys for other users' appointments and cancel or reschedule them via REST endpoints. Exploitation requires that the site has cancellation or rescheduling enabled, which are common configurations. The vulnerability affects all versions up to and including 2.7.6. No patch or official fix is currently documented.
Potential Impact
An attacker can bypass authorization controls to cancel or reschedule appointments belonging to other users without authentication. This results in unauthorized modification of appointment data (integrity impact) but does not disclose confidential information or cause denial of service. The impact is limited to integrity loss of appointment bookings.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, consider disabling the allow_cancellation and allow_rescheduling settings to prevent exploitation. Monitor for updates from the vendor regarding patches or official mitigations.
CVE-2026-9188: CWE-639 Authorization Bypass Through User-Controlled Key in wappointment Appointment Bookings for Zoom GoogleMeet and more – Wappointment
Description
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.
CVSS v3.1
Score 5.3medium
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-9188 describes an insecure direct object reference vulnerability in the Wappointment plugin for WordPress. The plugin uses an edit key for appointment authorization, generated as a predictable, unsalted MD5 hash of client_id (sequential integer), start_at (public timestamp), and staff_id (small enumerable integer). Because the key is predictable and no additional ownership or identity verification is performed, unauthenticated attackers can compute valid keys for other users' appointments and cancel or reschedule them via REST endpoints. Exploitation requires that the site has cancellation or rescheduling enabled, which are common configurations. The vulnerability affects all versions up to and including 2.7.6. No patch or official fix is currently documented.
Potential Impact
An attacker can bypass authorization controls to cancel or reschedule appointments belonging to other users without authentication. This results in unauthorized modification of appointment data (integrity impact) but does not disclose confidential information or cause denial of service. The impact is limited to integrity loss of appointment bookings.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, consider disabling the allow_cancellation and allow_rescheduling settings to prevent exploitation. Monitor for updates from the vendor regarding patches or official mitigations.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Wordfence
- Date Reserved
- 2026-05-21T15:04:38.302Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4634ad27e9c79719a6e420
Added to database: 07/02/2026, 09:51:41 UTC
Last enriched: 07/02/2026, 10:06:49 UTC
Last updated: 08/16/2026, 00:41:16 UTC
Views: 67
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