CVE-2026-93399

Online Scheduling and Appointment Booking System <= 28.2 - Insecure Direct Object Reference to Unauthenticated Arbitrary Booking Token Disclosure and Deletion via 'order_id' Parameter

2026-09-24 18:12
Theklis

Strategic Overview

Status
Patched in 28.3
Affected Version
<= 28.2
CVSS
9.1Critical
Weakness type
CWE-639 · Authorization Bypass Through User-Controlled Key
CVE
CVE-2026-93399
View all Online Scheduling and Appointment Booking System – Bookly vulnerabilities

At a glance

CVE-2026-93399 is a critical-severity Authorization Bypass Through User-Controlled Key vulnerability in the Online Scheduling and Appointment Booking System WordPress plugin, affecting versions <= 28.2. It carries a CVSS score of 9.1 (reachable over the network; low attack complexity; high integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 28.3; sites on affected versions should update now. Disclosed September 2026, reported by Theklis.

Vulnerability Overview

The Bookly plugin for WordPress is vulnerable to Insecure Direct Object Reference in versions up to, and including, 28.2 via the 'bookly_get_form_id', 'bookly_render_complete', 'bookly_add_to_calendar' and 'bookly_rollback_order' AJAX actions. This is due to the 'bookly_get_form_id' handler blindly storing the attacker-controlled 'order_id' from the submitted form_data into a new booking session, which the 'bookly_render_complete' handler then trusts to look up and return the corresponding Order's secret token without verifying that the current session created that order. This makes it possible for unauthenticated attackers to enumerate sequential order IDs, disclose other customers' order tokens, retrieve calendar/appointment information via 'bookly_add_to_calendar' and permanently delete arbitrary non-completed bookings via 'bookly_rollback_order', which cascade-deletes the customer_appointment and (when no other customers are attached) the underlying appointment.

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. A successful exploit has high impact on integrity, availability.

CWE-639: Authorization Bypass Through User-Controlled Key

Online Scheduling and Appointment Booking System <= 28.2 carries this weakness at bookly_get_form_id, and reaching it takes no account at all. 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 Online Scheduling and Appointment Booking System the fix is 28.3: builds <= 28.2 are affected, anything from 28.3 onward is not.

Remediation

Update to version 28.3, 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: Online Scheduling and Appointment Booking System 28.3 closes this, and updating the plugin is the step that ends it.

  • Login Security
  • Alerts

External References

Related records

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