Appointment Booking Plugin – LatePoint | Calendar & Scheduling for WordPress <= 5.6.9 - Authenticated (Subscriber+) Insecure Direct Object Reference to Arbitrary Customer PII Modification
Strategic Overview
- Status
- Patched in 5.6.10
- Affected Version
<= 5.6.9- CVSS
- 5.4Medium
- Weakness type
- CWE-639 · Authorization Bypass Through User-Controlled Key
- CVE
CVE-2026-17538
At a glance
CVE-2026-17538 is a medium-severity Authorization Bypass Through User-Controlled Key vulnerability in the Appointment Booking Plugin WordPress plugin, affecting versions <= 5.6.9. It carries a CVSS score of 5.4 (reachable over the network; low attack complexity). Exploitation requires an authenticated account at Subscriber level or above. The issue is fixed in version 5.6.10; sites on affected versions should update now. Disclosed October 2026, reported by owlmind.
Vulnerability Overview
The LatePoint - Appointment Booking & Reservation plugin for WordPress is vulnerable to Insecure Direct Object Reference in versions up to, and including, 5.6.9. This is due to the process_step_customer() function using is_user_logged_in() as the sole gate before merging POSTed customer data into an existing LatePoint customer, without any ownership checks. This makes it possible for authenticated attackers, with Subscriber-level access and above, to modify the personal information (first name, last name, email, phone, notes) of arbitrary LatePoint customers, and, when the contact_merge setting is 'phone', to overwrite the victim's email address and take over the account via a password reset.
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 interaction from a victim user.
CWE-639: Authorization Bypass Through User-Controlled Key
Appointment Booking Plugin <= 5.6.9 carries this weakness at phone, and reaching it takes an account at Subscriber level or above. Authorization bypass through a user-controlled key, often called insecure direct object reference, means the application looks up a record by an identifier from the request without checking that the caller owns it.
Changing a number in the request is enough to read or modify other users' records, which on commerce and membership sites means customer data. For Appointment Booking Plugin the fix is 5.6.10: builds <= 5.6.9 are affected, anything from 5.6.10 onward is not.
Remediation
Update to version 5.6.10, or a newer patched version
How does WordSec protect against this?
Because it turns on account access, WordSec's login security is the relevant layer: role-based two-factor, captcha and brute-force limits raise the cost of getting the account this needs. None of that substitutes for the fix: Appointment Booking Plugin 5.6.10 closes this, and updating the plugin is the step that ends it.
- Login Security
- Alerts
External References
Related records
Same weakness class
Other vulnerabilities in Appointment Booking Plugin – LatePoint | Calendar & Scheduling for WordPress
- 9.8CVE-2025-6715: LatePoint <= 5.1.93 Local File Inclusion
CVE-2025-6715 - 9.8CVE-2024-8943: LatePoint <= 5.0.12 Authentication Bypass
CVE-2024-8943 - 9.8CVE-2024-8911: LatePoint <= 5.0.11 Arbitrary User Password Change
CVE-2024-8911 - 9.1CVE-2026-110653: Appointment Booking Plugin Authentication Bypass
CVE-2026-110653 - 9.1CVE-2026-92966: Appointment Booking Arbitrary Shortcode Execution
CVE-2026-92966 - 8.8CVE-2026-104766: Appointment Booking Privilege Escalation
CVE-2026-104766 - 8.8CVE-2026-13228: LatePoint Privilege Escalation to Administrator
CVE-2026-13228 - 8.8CVE-2026-49083: LatePoint Privilege Escalation
CVE-2026-49083
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