# VikBooking Hotel Booking Engine & PMS <= 1.8.19 - Unauthenticated Stored Cross-Site Scripting via 'optionals' Parameter

- **ID:** WPSEC-2026-1857
- **Plugin:** VikBooking Hotel Booking Engine & PMS (`vikbooking`), https://wordpress.org/plugins/vikbooking/
- **Affected versions:** all versions before 1.8.20
- **Fixed in:** 1.8.20 (Update to 1.8.20 or later.)
- **Severity:** High 7.2 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N)
- **Weakness:** CWE-79
- **Usage among sites WPSec scans:** plugin Low, affected versions None seen (as of 2026-10-28)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/vikbooking
- **Fix released:** 2026-10-27
- **Published:** 2026-10-28
- **URL:** https://wpsec.com/vuln/WPSEC-2026-1857/

## Description

The VikBooking Hotel Booking Engine & PMS plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'optionals' parameter of the front-end booking flow in all versions up to, and including, 1.8.19 due to insufficient input sanitization and output escaping. Room option quantities supplied by the booker were not cast to integers before being stored with the reservation. They were later echoed unescaped into the value attribute of the admin edit-booking form. This makes it possible for unauthenticated attackers to inject arbitrary web scripts that execute whenever an administrator or staff member opens the affected reservation for editing.

## References

- https://wpsec.com/vuln/WPSEC-2026-1857/
- https://plugins.svn.wordpress.org/vikbooking/tags/1.8.20/
- https://wordpress.org/plugins/vikbooking/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-1857/

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.