CVE-2026-65052: Ninja Forms WordPress Auth Bypass Flaw

CVE-2026-65052 Overview

CVE-2026-65052 is an improper input validation vulnerability in the Ninja Forms WordPress plugin, affecting version 3.14.8 and prior. Unauthenticated attackers can inject arbitrary numeric values into form calculations and payment totals. The flaw resides in the get_calc_value() method, which fails open when submissions do not match any configured option in ListSelect or ListRadio fields. Attackers tamper with the AJAX submit endpoint payload to override admin-configured pricing logic. Successful exploitation lets adversaries manipulate payment amounts to zero or any arbitrary figure, bypassing e-commerce controls entirely. The vulnerability is classified under CWE-472: External Control of Assumed-Immutable Web Parameter.

Critical Impact
Unauthenticated attackers can alter payment totals on any WordPress site running vulnerable Ninja Forms versions, causing direct financial loss for site operators.

Affected Products

Ninja Forms WordPress plugin version 3.14.8
Ninja Forms WordPress plugin versions prior to 3.14.8
WordPress sites using Ninja Forms with ListSelect or ListRadio fields tied to calculations or payments

Discovery Timeline

2026-07-21 - CVE-2026-65052 published to NVD
2026-07-22 - Last updated in NVD database

Technical Details for CVE-2026-65052

Vulnerability Analysis

The vulnerability stems from insufficient validation of user-supplied field values in Ninja Forms' calculation engine. When a form submission arrives at the AJAX submit endpoint, the plugin invokes get_calc_value() to resolve numeric contributions from list-based fields. For ListSelect and ListRadio fields, the method compares submitted values against the field's configured options. If no match is found, the code fails open by returning the attacker-supplied value rather than rejecting the submission or falling back to a safe default.

This flaw directly enables business logic manipulation. An attacker crafting a modified payload can substitute the price contribution of a selected option with an arbitrary number, including zero or negative values. The calculation engine then feeds the tampered value into payment total computations, producing an incorrect grand total that the site processes as legitimate.

Root Cause

The root cause is a fail-open pattern in get_calc_value(). Instead of enforcing a strict allowlist against the field's admin-defined options, the function accepts unvalidated client input when no configured option matches. This violates the assumption that pricing values referenced by form fields remain immutable from the client side, which is the exact scenario described by CWE-472.

Attack Vector

Exploitation requires no authentication. An attacker intercepts a legitimate form submission or crafts one directly against the Ninja Forms AJAX endpoint. The attacker modifies the value fields associated with ListSelect or ListRadio inputs to values not present in the option set. The server-side calculation logic accepts the injected numeric value and applies it to the payment total. See the VulnCheck Ninja Forms Advisory for technical details on the payload structure.

Detection Methods for CVE-2026-65052

Indicators of Compromise

Ninja Forms submissions where ListSelect or ListRadio field values do not match any configured option in the form definition
Payment transactions with totals significantly below expected pricing tiers, including zero-value orders for paid products
Repeated POST requests to admin-ajax.php with action=nf_ajax_submit from a single client showing modified numeric payloads
Order records where line-item calculations diverge from the sum of configured option prices

Detection Strategies

Correlate Ninja Forms submission logs against the plugin's stored field option definitions to identify value mismatches
Deploy web application firewall rules that validate submitted list field values against known option sets before they reach WordPress
Review payment gateway logs for anomalously low transaction amounts tied to Ninja Forms order IDs

Monitoring Recommendations

Enable verbose logging on the Ninja Forms AJAX submit endpoint and forward records to a central log platform
Alert on submissions containing numeric values in listselect or listradio fields that do not appear in the form's configured options
Monitor for spikes in zero-total or low-total completed transactions after any Ninja Forms deployment

How to Mitigate CVE-2026-65052

Immediate Actions Required

Update Ninja Forms to a version later than 3.14.8 as soon as the vendor releases a patched release listed in the Ninja Forms changelog
Audit recent form submissions and payment records for tampered totals, especially zero-value orders
Temporarily disable public-facing forms that use ListSelect or ListRadio fields tied to payment calculations until patched

Patch Information

Refer to the Ninja Forms plugin page and the official changelog for the fixed release. Apply the update through the WordPress admin plugin manager or via WP-CLI to all affected sites.

Workarounds

Replace ListSelect and ListRadio fields used for pricing with server-side lookups that do not rely on client-submitted numeric values
Add a web application firewall rule that rejects Ninja Forms submissions whose list field values do not match the plugin's stored option set
Enforce payment total validation at the gateway or checkout layer by recalculating totals from a trusted product catalog before charging

bash

# WP-CLI example: update Ninja Forms across all sites once a fixed version is available
wp plugin update ninja-forms --version=<patched_version>
wp plugin list --name=ninja-forms --fields=name,status,version