CVE-2026-11567: SureForms WordPress Auth Bypass Flaw

CVE-2026-11567 Overview

CVE-2026-11567 is a business logic vulnerability in the SureForms WordPress plugin before version 2.11.1. The plugin fails to properly validate payment amounts on forms configured with dynamically-sourced payment values, such as variable or hidden fields. Unauthenticated attackers can manipulate the submitted amount and underpay for the configured product or subscription. Forms using a fixed configured price are not affected by this issue.

Critical Impact
Unauthenticated attackers can tamper with client-side payment amount fields to purchase products or subscriptions for less than the intended price, resulting in direct financial loss to site operators.

Affected Products

SureForms WordPress plugin versions prior to 2.11.1
WordPress sites using SureForms with variable payment amount configurations
WordPress sites using SureForms with hidden field payment amount configurations

Discovery Timeline

2026-07-14 - CVE-2026-11567 published to NVD
2026-07-14 - Last updated in NVD database

Technical Details for CVE-2026-11567

Vulnerability Analysis

The vulnerability is a business logic flaw in the payment processing workflow of SureForms. When a form is configured to accept a payment amount from a dynamic source, the plugin trusts the client-supplied value without server-side validation against the intended product or subscription price. An attacker can intercept the form submission and modify the payment amount field to any value, including significantly reduced amounts.

The issue affects only forms where the payment amount is variable or bound to a hidden field. Forms with a hard-coded, fixed price enforce the correct amount server-side and remain unaffected. Because the vulnerability requires the site owner to have configured a dynamic payment amount, exploitation depends on the target site's specific form configuration.

Root Cause

The root cause is missing server-side validation of the payment amount before payment gateway processing. The plugin accepts the amount submitted by the client without cross-referencing the value against the authoritative product or subscription price stored on the server. This is a classic Business Logic Error where trust boundaries between client-supplied data and payment processing are not enforced.

Attack Vector

Exploitation requires no authentication and can be performed over the network. An attacker loads a vulnerable form in a browser, intercepts the HTTP POST submission using a proxy such as Burp Suite, and modifies the payment amount parameter before forwarding the request. The payment gateway then processes the attacker-controlled amount as valid. The high attack complexity reflects the need for the target site to have a dynamic payment form configured and for the attacker to identify the correct field to manipulate.

No verified proof-of-concept code has been published. Technical details are documented in the WPScan Vulnerability Report.

Detection Methods for CVE-2026-11567

Indicators of Compromise

Payment gateway transactions with amounts inconsistent with configured product or subscription prices
Multiple low-value payments originating from the same IP address or user agent
Successful order completions where the recorded amount differs from the SureForms product catalog price
HTTP POST requests to SureForms submission endpoints containing modified amount parameters

Detection Strategies

Reconcile payment gateway records against expected SureForms product prices to identify underpayments
Enable verbose logging on the WordPress site to capture full POST bodies for form submissions
Alert on any completed order where the final charged amount is below the minimum configured product price
Review web server access logs for repeated submissions to SureForms endpoints from single sources

Monitoring Recommendations

Monitor SureForms plugin version across all WordPress deployments to identify versions before 2.11.1
Track new form creations that use variable or hidden payment amount fields
Correlate WordPress application logs with payment processor callbacks to detect amount mismatches
Establish a baseline of average transaction values and alert on statistical outliers

How to Mitigate CVE-2026-11567

Immediate Actions Required

Update the SureForms plugin to version 2.11.1 or later on all WordPress installations
Audit existing forms to identify any using variable or hidden payment amount configurations
Review payment gateway transaction history for the past several months to identify potential underpayments
Contact your payment processor to reverse or reconcile any confirmed fraudulent low-value transactions

Patch Information

The vendor released version 2.11.1 of the SureForms plugin, which addresses this vulnerability by adding server-side validation of payment amounts on forms with dynamically-sourced values. Refer to the WPScan Vulnerability Report for the full disclosure details.

Workarounds

Reconfigure affected forms to use fixed configured prices instead of variable or hidden payment amounts until the patch is applied
Temporarily disable payment forms that rely on dynamic amounts if immediate patching is not possible
Implement web application firewall rules to inspect and validate payment amount parameters in requests to SureForms endpoints
Add manual review workflow for orders below expected minimum thresholds before fulfillment

bash

# Update SureForms via WP-CLI
wp plugin update sureforms --version=2.11.1

# Verify installed version
wp plugin get sureforms --field=version