# TrueBooker – Appointment Booking and Scheduler System <= 1.2.9 - Unauthenticated Insecure Direct Object Reference to Booking Summary Disclosure

- **ID:** WPSEC-2026-0833
- **Plugin:** TrueBooker – Appointment Booking and Scheduler System (`truebooker-appointment-booking`), https://wordpress.org/plugins/truebooker-appointment-booking/
- **Affected versions:** all versions before 1.3.0
- **Fixed in:** 1.3.0 (Update to 1.3.0 or later.)
- **Severity:** Medium 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)
- **Weakness:** CWE-639
- **Usage among sites WPSec scans:** plugin Low, affected versions Low (as of 2026-10-13)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/truebooker-appointment-booking
- **Fix released:** 2026-10-12
- **Published:** 2026-10-13
- **URL:** https://wpsec.com/vuln/WPSEC-2026-0833/

## Description

The truebooker-appointment-booking plugin for WordPress is vulnerable to Insecure Direct Object Reference via the 'refappbkd' parameter of the [truebooker-bookingform] shortcode in all versions up to, and including, 1.2.9, due to the booking reference being only a base64-encoded sequential booking ID with no ownership check or signature. This makes it possible for unauthenticated attackers to view the booking summary of other customers' bookings whose summary has not been viewed yet, including name, address, email, phone and appointment details, and to trigger the booking confirmation emails.

## References

- https://wpsec.com/vuln/WPSEC-2026-0833/
- https://plugins.svn.wordpress.org/truebooker-appointment-booking/tags/1.3.0/
- https://wordpress.org/plugins/truebooker-appointment-booking/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-0833/

License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Free to use, share and adapt, also commercially, if you credit WPSec and link to this advisory.