CVE-2026-1947: NEX-Forms WordPress Auth Bypass Vulnerability

CVE-2026-1947 Overview

The NEX-Forms – Ultimate Forms Plugin for WordPress is vulnerable to Insecure Direct Object Reference (IDOR) in all versions up to, and including, 9.1.9 via the submit_nex_form() function due to missing validation on a user controlled key. This makes it possible for unauthenticated attackers to overwrite arbitrary form entries via the nf_set_entry_update_id parameter.

Critical Impact

Unauthenticated attackers can manipulate and overwrite any form submission data stored by the NEX-Forms plugin, potentially compromising data integrity across all forms on affected WordPress sites.

Affected Products

• NEX-Forms – Ultimate Forms Plugin for WordPress versions up to and including 9.1.9

Discovery Timeline

• 2026-03-16 - CVE CVE-2026-1947 published to NVD
• 2026-03-16 - Last updated in NVD database

Technical Details for CVE-2026-1947

Vulnerability Analysis

This vulnerability is classified as CWE-639 (Authorization Bypass Through User-Controlled Key), commonly known as Insecure Direct Object Reference (IDOR). The core issue lies in the submit_nex_form() function, which fails to properly validate user-controlled input before using it to reference form entry records.

When a user submits a form, the plugin accepts an nf_set_entry_update_id parameter that directly references a form entry in the database. Because the application does not verify whether the requesting user has authorization to modify the specified entry, attackers can manipulate this parameter to target any existing form entry regardless of ownership.

The network-accessible nature of this vulnerability combined with the lack of authentication requirements makes it particularly dangerous for WordPress installations that rely on NEX-Forms for collecting sensitive information such as contact details, registration data, or payment-related forms.

Root Cause

The root cause of this vulnerability is the absence of authorization checks in the submit_nex_form() function. The function accepts the nf_set_entry_update_id parameter directly from user input and uses it to identify which form entry to update, without verifying that the current user has permission to modify that specific record. This violates the principle of least privilege and allows any unauthenticated user to reference and modify arbitrary form entries.

Attack Vector

The attack vector for CVE-2026-1947 is network-based, requiring no authentication or user interaction. An attacker can craft malicious HTTP requests to the WordPress site targeting the form submission endpoint. By manipulating the nf_set_entry_update_id parameter value, the attacker can specify any form entry ID in the database. Since the vulnerable function does not perform ownership validation, the attacker's submitted data will overwrite the targeted entry, regardless of who originally created it.

This could be exploited to corrupt business-critical form data, tamper with order information, modify contact submissions, or manipulate any other data stored through NEX-Forms.

Detection Methods for CVE-2026-1947

Indicators of Compromise

• Unusual modification timestamps on form entries without corresponding user sessions
• Form entry data that appears inconsistent or tampered with
• Web server logs showing repeated form submissions with varying nf_set_entry_update_id values
• Access patterns indicating enumeration of form entry IDs

Detection Strategies

• Monitor web application firewall (WAF) logs for suspicious form submission patterns targeting NEX-Forms endpoints
• Implement anomaly detection for form entry modifications, flagging updates from unexpected IP addresses or sessions
• Review WordPress database audit logs for bulk or sequential modifications to NEX-Forms entry tables

Monitoring Recommendations

• Enable detailed logging for all form submission activities in WordPress
• Configure alerting for form entry modifications that occur outside normal business hours
• Implement rate limiting on form submission endpoints to slow enumeration attempts

How to Mitigate CVE-2026-1947

Immediate Actions Required

• Update NEX-Forms – Ultimate Forms Plugin to a version newer than 9.1.9 immediately
• Review existing form entries for signs of unauthorized modification
• Consider temporarily disabling the plugin if immediate patching is not possible
• Implement web application firewall rules to filter requests containing suspicious nf_set_entry_update_id patterns

Patch Information

The vulnerability has been addressed in versions released after 9.1.9. The WordPress Plugin Change Log contains details about the security fix. Additional vulnerability information is available through the Wordfence Vulnerability Report.

Site administrators should update the plugin through the WordPress admin dashboard or by downloading the latest version from the WordPress plugin repository.

Workarounds

• Restrict access to form submission endpoints using server-level access controls or .htaccess rules
• Implement additional validation layers using a security plugin to inspect form submission parameters
• Consider using a web application firewall to block requests with suspicious parameter patterns targeting form entry IDs

# Example .htaccess rule to add rate limiting on form submissions
# Add to WordPress root .htaccess file
<IfModule mod_rewrite.c>
    RewriteEngine On
    # Log suspicious form submission patterns for review
    RewriteCond %{QUERY_STRING} nf_set_entry_update_id [NC]
    RewriteRule .* - [E=SUSPICIOUS_FORM:1]
</IfModule>