# Booking Calendar <= 11.9 - Missing Authorization to Unauthenticated Block Times Availability Timeline Disclosure

- **ID:** WPSEC-2026-0807
- **Plugin:** Booking Calendar (`booking`), https://wordpress.org/plugins/booking/
- **Affected versions:** all versions before 11.9.1
- **Fixed in:** 11.9.1 (Update to 11.9.1 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-862
- **Usage among sites WPSec scans:** plugin Medium, affected versions Medium (as of 2026-10-12)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/booking
- **Fix released:** 2026-10-11
- **Published:** 2026-10-12
- **URL:** https://wpsec.com/vuln/WPSEC-2026-0807/

## Description

The Booking Calendar plugin for WordPress is vulnerable to unauthorized access of data via the WPBC_AJX_AVAILABILITY_TIMESLOTS_READ AJAX action in all versions up to, and including, 11.9, due to a missing capability check and missing nonce validation on the wpbc_availability_timeslots_ajax_read function, which was also registered for logged-out users. This makes it possible for unauthenticated attackers to read the Block Times (Time Slots Availability) administration timeline for any booking resource, including administrator-blocked time intervals and the IDs, approval status and time ranges of existing bookings.

## References

- https://wpsec.com/vuln/WPSEC-2026-0807/
- https://plugins.svn.wordpress.org/booking/tags/11.9.1/
- https://wordpress.org/plugins/booking/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-0807/

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.