CVE-2024-50428: Multi Step Form Auth Bypass Vulnerability

CVE-2024-50428 Overview

CVE-2024-50428 is a Missing Authorization vulnerability affecting the Mondula Multi Step Form plugin for WordPress. This broken access control flaw allows attackers to exploit incorrectly configured access control security levels, potentially enabling unauthorized actions on vulnerable WordPress installations. The vulnerability stems from missing authorization checks (CWE-862), which permits unauthenticated users to perform privileged operations that should be restricted.

Critical Impact

This vulnerability allows remote unauthenticated attackers to bypass access controls and perform unauthorized actions on WordPress sites running the affected Multi Step Form plugin, potentially leading to complete site compromise.

Affected Products

• Mondula Multi Step Form plugin for WordPress version 1.7.21 and earlier
• WordPress installations utilizing the multi-step-form plugin

Discovery Timeline

• 2024-10-29 - CVE-2024-50428 published to NVD
• 2026-04-01 - Last updated in NVD database

Technical Details for CVE-2024-50428

Vulnerability Analysis

This vulnerability exists due to missing authorization checks within the Mondula Multi Step Form WordPress plugin. The plugin fails to properly verify user permissions before allowing access to sensitive functionality, creating a broken access control condition. Without proper authorization validation, the plugin permits unauthenticated users to access administrative or privileged endpoints that should require authentication and appropriate user roles.

The impact of this vulnerability is severe as it can lead to unauthorized modification of form configurations, data exfiltration of submitted form entries, or manipulation of plugin settings. Given the plugin's function of handling multi-step forms, attackers could potentially access sensitive user-submitted data or modify form behavior for malicious purposes such as phishing or data harvesting.

Root Cause

The root cause of CVE-2024-50428 is the absence of proper capability checks and nonce verification in critical plugin functions. WordPress plugins should implement current_user_can() checks to verify user permissions before executing privileged operations, along with nonce validation to prevent unauthorized requests. The Multi Step Form plugin lacks these essential security controls, allowing any user—including unauthenticated visitors—to invoke restricted functionality.

Attack Vector

The attack is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability remotely by sending crafted HTTP requests directly to vulnerable WordPress AJAX handlers or REST API endpoints exposed by the plugin. Due to the missing authorization checks, these requests are processed without validating that the requester has appropriate permissions.

The vulnerability manifests in AJAX action handlers that process form management operations without verifying user capabilities. Attackers can enumerate and target these endpoints to perform unauthorized actions. For detailed technical information, see the Patchstack WordPress Vulnerability Advisory.

Detection Methods for CVE-2024-50428

Indicators of Compromise

• Unexpected modifications to Multi Step Form plugin configurations or form definitions
• Unauthorized access to form submission data or export activities
• Anomalous HTTP requests to WordPress AJAX endpoints containing multi-step-form action parameters
• Unusual administrative actions in WordPress logs without corresponding authenticated sessions

Detection Strategies

• Monitor WordPress AJAX endpoint access logs for requests to Multi Step Form plugin actions from unauthenticated sessions
• Implement Web Application Firewall (WAF) rules to detect and block suspicious requests targeting admin-ajax.php with Multi Step Form action parameters
• Review WordPress database for unauthorized changes to plugin configuration tables
• Deploy file integrity monitoring to detect unauthorized plugin file modifications

Monitoring Recommendations

• Enable detailed WordPress access logging and review logs for patterns of exploitation attempts
• Configure alerting for any administrative changes to Multi Step Form plugin settings
• Monitor for bulk data access patterns that may indicate form submission data exfiltration
• Implement real-time security monitoring with SentinelOne Singularity to detect post-exploitation activity

How to Mitigate CVE-2024-50428

Immediate Actions Required

• Update the Multi Step Form plugin to the latest patched version immediately
• Audit existing form configurations and submission data for signs of unauthorized access
• Review WordPress user accounts for any unauthorized additions or privilege escalations
• Implement a Web Application Firewall to add an additional layer of protection for WordPress sites

Patch Information

Site administrators should update the Mondula Multi Step Form plugin to a version newer than 1.7.21. Check the WordPress plugin repository or the official Mondula website for the latest security update. Before updating, create a full backup of your WordPress installation including the database.

For the latest patch information and security guidance, refer to the Patchstack WordPress Vulnerability Advisory.

Workarounds

• If immediate patching is not possible, temporarily deactivate the Multi Step Form plugin until an update can be applied
• Restrict access to WordPress admin AJAX endpoints using server-level access controls or .htaccess rules
• Implement additional authentication layers for WordPress administration using security plugins
• Monitor and audit all plugin activity until the vulnerability is remediated

# Temporary mitigation - restrict AJAX access to authenticated users only
# Add to .htaccess in WordPress root directory
<Files admin-ajax.php>
    Order deny,allow
    Deny from all
    # Allow specific trusted IPs
    Allow from 192.168.1.0/24
</Files>