CVE-2026-24544: HD Quiz Authorization Bypass Vulnerability

CVE-2026-24544 Overview

CVE-2026-24544 is a Missing Authorization vulnerability affecting the HD Quiz WordPress plugin developed by Harmonic Design. This Broken Access Control flaw allows authenticated attackers to exploit incorrectly configured access control security levels, potentially exposing sensitive quiz data or functionality that should be restricted to higher-privileged users.

The vulnerability stems from inadequate authorization checks within the plugin's functionality, classified under CWE-862 (Missing Authorization). Attackers with low-level privileges can bypass intended access restrictions to access resources or perform actions beyond their authorized scope.

Critical Impact

Authenticated users with minimal privileges can exploit missing authorization checks to access restricted quiz functionality and potentially sensitive data in WordPress installations running vulnerable versions of HD Quiz.

Affected Products

• Harmonic Design HD Quiz WordPress Plugin versions up to and including 2.0.9
• WordPress installations with vulnerable HD Quiz plugin installed
• Sites using HD Quiz for quiz functionality without updated security patches

Discovery Timeline

• 2026-01-23 - CVE-2026-24544 published to NVD
• 2026-01-27 - Last updated in NVD database

Technical Details for CVE-2026-24544

Vulnerability Analysis

This vulnerability represents a classic Broken Access Control issue where the HD Quiz plugin fails to implement proper authorization checks before allowing access to certain functionality. When a user makes a request to access specific plugin features or data, the application does not adequately verify whether the authenticated user has the appropriate permissions to perform the requested action.

The impact allows low-privileged authenticated users to potentially read confidential information that should only be accessible to administrators or higher-privileged roles. This could include quiz answers, user submission data, or plugin configuration settings depending on the specific endpoints affected.

Root Cause

The root cause is classified as CWE-862: Missing Authorization. The HD Quiz plugin lacks proper capability checks or nonce verification on certain AJAX handlers or administrative functions. WordPress plugins should implement current_user_can() checks to verify user capabilities before processing requests, but the vulnerable versions of HD Quiz fail to implement these checks consistently across all sensitive functionality.

Attack Vector

The attack is network-based and requires the attacker to have a valid authenticated session on the WordPress site, even with minimal privileges such as a subscriber role. The attacker can directly access plugin endpoints or AJAX handlers that lack proper authorization validation. No user interaction is required beyond the attacker's own actions, and the scope is unchanged meaning the impact is contained within the vulnerable component.

The attack flow typically involves:

1. Attacker authenticates to WordPress with a low-privilege account
2. Attacker identifies HD Quiz AJAX endpoints or admin functions lacking authorization
3. Attacker crafts direct requests to these endpoints
4. The plugin processes requests without verifying user capabilities
5. Attacker gains access to restricted data or functionality

For detailed technical analysis, see the Patchstack Vulnerability Advisory.

Detection Methods for CVE-2026-24544

Indicators of Compromise

• Unusual access patterns to HD Quiz AJAX endpoints from low-privileged user accounts
• Subscriber or contributor roles accessing quiz administrative data or settings
• Unexpected requests to admin-ajax.php with HD Quiz action parameters from non-admin users
• Anomalous data exports or quiz result access by unauthorized users

Detection Strategies

• Monitor WordPress AJAX requests for HD Quiz actions originating from low-privileged user sessions
• Implement logging for all HD Quiz administrative function calls with user capability tracking
• Review access logs for patterns indicating unauthorized access to quiz management endpoints
• Deploy Web Application Firewall (WAF) rules to detect and alert on suspicious plugin endpoint access

Monitoring Recommendations

• Enable WordPress debug logging to capture unauthorized access attempts
• Configure security plugins to alert on privilege escalation patterns
• Regularly audit user activity logs for anomalous HD Quiz-related actions
• Implement real-time monitoring of AJAX handlers associated with the HD Quiz plugin

How to Mitigate CVE-2026-24544

Immediate Actions Required

• Update HD Quiz plugin to the latest version that addresses this vulnerability
• Review and audit user roles on WordPress sites using HD Quiz to minimize attack surface
• Temporarily disable HD Quiz plugin if an update is not available and functionality is non-critical
• Implement additional access controls at the web server or WAF level

Patch Information

Administrators should check the WordPress plugin repository for updated versions of HD Quiz that address this broken access control vulnerability. Version 2.0.9 and all prior versions are confirmed vulnerable. Consult the Patchstack advisory for the latest remediation guidance and patch availability.

Workarounds

• Restrict user registration on WordPress sites to reduce the authenticated attack surface
• Implement additional capability checks via custom code or security plugins
• Use a WordPress security plugin to add authorization layers to AJAX endpoints
• Consider temporarily removing the HD Quiz plugin until a patched version is available

# Disable HD Quiz plugin via WP-CLI until patched
wp plugin deactivate hd-quiz

# Verify current installed version
wp plugin list --name=hd-quiz --fields=name,version,status

# Update plugin when patch is available
wp plugin update hd-quiz