Appointment Booking Calendar <= 1.6.11.8 - Missing Authorization to Unauthenticated Arbitrary Modification via Bulk Appointments REST API Endpoint
Strategic Overview
- Status
- Patched in 1.6.11.9
- Affected Plugin
- Simply Schedule Appointments
- Affected Version
<= 1.6.11.8- CVSS
- 5.3Medium
- Weakness type
- CWE-862 · Missing Authorization
- CVE
CVE-2026-6937
At a glance
CVE-2026-6937 is a medium-severity Missing Authorization vulnerability in the Simply Schedule Appointments WordPress plugin, affecting versions <= 1.6.11.8. It carries a CVSS score of 5.3 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 1.6.11.9; sites on affected versions should update now. Disclosed May 2026, reported by winrace.
Vulnerability Overview
The Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin plugin for WordPress is vulnerable to Missing Authorization in all versions up to, and including, 1.6.11.8 due to the plugin not properly verifying that a user is authorized to perform an action via the bulk appointments REST API endpoint. This makes it possible for unauthenticated attackers to modify arbitrary appointment records including customer PII, payment status, and meeting URL fields, and to expose full customer PII from existing appointment records via the bulk endpoint response. The public nonce is a static, user-independent value present in the HTML source of any page hosting the [ssa_booking] shortcode, meaning any visitor who has viewed such a page can obtain it and target any appointment in the system without authentication.
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user.
CWE-862: Missing Authorization
Reaching this weakness in Simply Schedule Appointments <= 1.6.11.8 takes no account at all. A missing authorization check means a function is reachable by anyone who can reach the endpoint, because the code never asks whether the caller is allowed to perform the action.
Any user who can reach the endpoint gets to run an action reserved for higher-privileged roles, from reading protected data to changing settings or content. For Simply Schedule Appointments the fix is 1.6.11.9: builds <= 1.6.11.8 are affected, anything from 1.6.11.9 onward is not.
Remediation
Update to version 1.6.11.9, or a newer patched version
How does WordSec protect against this?
This one needs no account at all, which puts it outside what login hardening can reach; WordSec's login security narrows the account-level paths around it, and the firewall is what inspects the request itself. None of that substitutes for the fix: Simply Schedule Appointments 1.6.11.9 closes this, and updating the plugin is the step that ends it.
- Login Security
- Alerts
External References
Related records
Same weakness class
- 7.5CVE-2026-3045: Appointment Booking… Unauthenticated Info Exposure
CVE-2026-3045 - 6.5CVE-2026-4807: Appointment Booking Calendar Arbitrary Appointment
CVE-2026-4807 - 5.3CVE-2026-57812: Appointment Booking Calendar Missing Authorization
CVE-2026-57812 - 5.3CVE-2026-59523: Appointment Booking Calendar Missing Authorization
CVE-2026-59523
Other vulnerabilities in Simply Schedule Appointments
- 8.8CVE-2024-2342: Appointment Booking Calendar SQL Injection
CVE-2024-2342 - 8.8CVE-2024-2341: Appointment Booking Calendar SQL Injection
CVE-2024-2341 - 7.5CVE-2026-65508: Simply Schedule Appointments SQL Injection
CVE-2026-65508 - 7.5CVE-2026-7797: Appointment Booking Calendar <= 1.6.11.8 SQL Injection
CVE-2026-7797 - 7.5CVE-2026-39493: Appointment Booking Calendar SQL Injection
CVE-2026-39493 - 7.5CVE-2026-3658: Appointment Booking Calendar <= 1.6.10.0 SQL Injection
CVE-2026-3658 - 7.5CVE-2026-1708: Appointment Booking Calendar <= 1.6.9.27 SQL Injection
CVE-2026-1708 - 7.5CVE-2025-12166: Simply Schedule Appointments <= 1.6.9.9 SQL Injection
CVE-2025-12166
Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C