CVE-2026-17567

Fluent Forms <= 6.2.8 - Unauthenticated Sensitive Information Exposure via Insecure Direct Object Reference and Weak Transaction Hash in 'transaction' Parameter

2026-07-30 21:02
ChinhNguyen

Strategic Overview

Status
Patched in 6.2.9
Affected Version
<= 6.2.8
CVSS
5.3Medium
Weakness type
CWE-639 · Authorization Bypass Through User-Controlled Key
CVE
CVE-2026-17567
View all Fluent Forms – Customizable Contact Forms, Survey, Quiz, & Conversational Form Builder vulnerabilities

At a glance

CVE-2026-17567 is a medium-severity Authorization Bypass Through User-Controlled Key vulnerability in the Fluent Forms WordPress plugin, affecting versions <= 6.2.8. It carries a CVSS score of 5.3 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 6.2.9; sites on affected versions should update now. Disclosed July 2026, reported by ChinhNguyen.

Vulnerability Overview

The Fluent Forms – Customizable Contact Forms, Survey, Quiz, & Conversational Form Builder plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 6.2.8 via the 'transaction' parameter due to missing validation on a user controlled key. This makes it possible for unauthenticated attackers to brute-force valid transaction hashes and view sensitive payment receipt data including customer name, email address, billing address, order items, payment method, and payment status belonging to other users. Because submission ID, form ID, and transaction creation time are either observable or guessable by an attacker, the effective brute-force space is bounded to approximately 900 candidates per second per (submission, form) pair, making exploitation practical without any prior authentication or account.

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.

CWE-639: Authorization Bypass Through User-Controlled Key

Fluent Forms <= 6.2.8 carries this weakness at transaction, 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 Fluent Forms the fix is 6.2.9: builds <= 6.2.8 are affected, anything from 6.2.9 onward is not.

Remediation

Update to version 6.2.9, 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: Fluent Forms 6.2.9 closes this, and updating the plugin is the step that ends it.

  • Login Security
  • Alerts

External References

Related records

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