WordPress · Wappointment · CVE-2026-9188
**Name of the Vulnerable Software and Affected Versions**
Wappointment versions prior to 2.7.7
**Description**
The plugin contains an Insecure Direct Object Reference (IDOR) flaw involving the `appointmentkey` parameter. The issue stems from the `edit key` used by the `tryCancel()` function being generated as a predictable, unsalted MD5 hash of the `client id` (a sequential integer), `start at` (a public timestamp), and `staff id` (an enumerable integer). Because the unauthenticated cancellation and rescheduling REST endpoints do not verify ownership beyond this reconstructible key, attackers can compute valid keys for other users to cancel or reschedule appointments. This exploitation is possible when the `allow cancellation` or `allow rescheduling` settings are enabled.
**Recommendations**
Update to a version newer than 2.7.6.
As a temporary mitigation, disable the `allow cancellation` and `allow rescheduling` settings.