# Fluent Forms <= 6.2.15 - Unauthenticated Payment Bypass via Oversized Payment Amounts, Quantities and Checkbox Values

- **ID:** WPSEC-2026-1193
- **Plugin:** Fluent Forms – Customizable Contact Forms, Survey, Quiz, & Conversational Form Builder (`fluentform`), https://wordpress.org/plugins/fluentform/
- **Affected versions:** all versions before 6.2.16
- **Fixed in:** 6.2.16 (Update to 6.2.16 or later.)
- **Severity:** Medium 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N)
- **Weakness:** CWE-20
- **Usage among sites WPSec scans:** plugin High, affected versions High (as of 2026-10-17)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/fluentform
- **Fix released:** 2026-10-16
- **Published:** 2026-10-17
- **URL:** https://wpsec.com/vuln/WPSEC-2026-1193/

## Description

The Fluent Forms plugin for WordPress is vulnerable to a payment bypass via payment form inputs in all versions up to, and including, 6.2.15, due to insufficient validation of user-supplied payment amounts, custom subscription values, item quantities and checkbox payment item values. Infinite or oversized numbers (such as 1e400) passed the positive-number check, and scalar checkbox values passed the option check. This makes it possible for unauthenticated attackers to submit values that make the stored order total zero or drop server-priced items, so the payment gateway is skipped and paid items or services are obtained for free.

## References

- https://wpsec.com/vuln/WPSEC-2026-1193/
- https://plugins.svn.wordpress.org/fluentform/tags/6.2.16/
- https://wordpress.org/plugins/fluentform/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-1193/

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.