CVE-2026-2428

Fluent Forms Pro Add On Pack <= 6.1.17 - Missing Authorization to Unauthenticated Payment Status modification

2026-02-26 14:33

Strategic Overview

Status: Patched in 6.1.18
Affected Plugin: Fluent Forms Pro Add On Pack
Affected Version: <= 6.1.17
CVSS: 7.5High
Weakness type: CWE-345 · Insufficient Verification of Data Authenticity
CVE: CVE-2026-2428

View all Fluent Forms Pro Add On Pack vulnerabilities

At a glance

CVE-2026-2428 is a high-severity Insufficient Verification of Data Authenticity vulnerability in the Fluent Forms Pro Add On Pack WordPress plugin, affecting versions <= 6.1.17. It carries a CVSS score of 7.5 (reachable over the network; low attack complexity; high integrity impact). Exploitation requires no authentication. The issue is fixed in version 6.1.18; sites on affected versions should update now. Disclosed February 2026, reported by Prickly Cactus.

Vulnerability Overview

The Fluent Forms Pro Add On Pack plugin for WordPress is vulnerable to Insufficient Verification of Data Authenticity in all versions up to, and including, 6.1.17. This is due to the PayPal IPN (Instant Payment Notification) verification being disabled by default (`disable_ipn_verification` defaults to `'yes'` in `PayPalSettings.php`). This makes it possible for unauthenticated attackers to send forged PayPal IPN notifications to the publicly accessible IPN endpoint, marking unpaid form submissions as "paid" and triggering post-payment automation (emails, access grants, digital product delivery).

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. A successful exploit has high impact on integrity.

CWE-345: Insufficient Verification of Data Authenticity

The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.

Remediation

Update to version 6.1.18, 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 Pro Add On Pack 6.1.18 closes this, and updating the plugin is the step that ends it.

Login Security
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-2428 https://www.wordfence.com/threat-intel/vulnerabilities/id/e5c62e54-da06-4b44-ba70-63065e664b0d https://nvd.nist.gov/vuln/detail/CVE-2026-2428

Related records

Other vulnerabilities in Fluent Forms Pro Add On Pack

CVSS Vector

7.5

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityNone
IntegrityHigh
AvailabilityNone

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