CVE-2026-39657: leadlovers Forms Auth Bypass Vulnerability

CVE-2026-39657 Overview

CVE-2026-39657 is a Missing Authorization vulnerability affecting the leadlovers forms WordPress plugin. This security flaw allows attackers to exploit incorrectly configured access control security levels, potentially gaining unauthorized access to protected functionality within the plugin. The vulnerability stems from a lack of proper authorization checks (CWE-862), enabling unauthenticated users to access resources that should require proper authentication and permissions.

Critical Impact

Attackers can bypass access controls in the leadlovers forms plugin to access protected functionality without authentication, potentially exposing sensitive form data and configurations.

Affected Products

• leadlovers forms WordPress plugin versions up to and including 1.0.2

Discovery Timeline

• April 8, 2026 - CVE-2026-39657 published to NVD
• April 9, 2026 - Last updated in NVD database

Technical Details for CVE-2026-39657

Vulnerability Analysis

This vulnerability is classified as a Broken Access Control issue, specifically involving missing authorization checks within the leadlovers forms WordPress plugin. The plugin fails to properly verify user permissions before allowing access to certain functionality, which means that attackers can interact with protected features without being authenticated or having the necessary privileges.

The network-based attack vector allows remote exploitation without requiring any user interaction. An attacker can craft requests directly to vulnerable endpoints, bypassing the intended access control mechanisms. While the impact is limited to information disclosure (confidentiality), this could expose sensitive form submissions, configuration data, or other protected information managed by the plugin.

Root Cause

The root cause of this vulnerability is the absence of proper authorization checks (CWE-862 - Missing Authorization) in the plugin's code. WordPress plugins typically need to implement capability checks using functions like current_user_can() to verify that users have appropriate permissions before executing sensitive operations. The leadlovers forms plugin fails to implement these checks on certain endpoints or functions, allowing unauthorized access.

Attack Vector

The vulnerability can be exploited over the network without requiring authentication or user interaction. An attacker would identify the vulnerable endpoints within the leadlovers forms plugin and directly access them, bypassing any intended access restrictions. Since no special privileges are required, any remote attacker can attempt exploitation.

The attack flow typically involves:

1. Identifying a WordPress installation using the leadlovers forms plugin
2. Locating the unprotected AJAX handlers or REST API endpoints
3. Sending crafted requests to access protected functionality
4. Extracting sensitive information such as form submissions or configuration data

For detailed technical information about this vulnerability, refer to the Patchstack Vulnerability Advisory.

Detection Methods for CVE-2026-39657

Indicators of Compromise

• Unusual requests to leadlovers forms plugin AJAX handlers from unauthenticated sessions
• Unexpected access patterns to plugin-specific endpoints in web server logs
• Multiple requests attempting to enumerate or access form data without valid authentication cookies

Detection Strategies

• Monitor WordPress access logs for requests to /wp-admin/admin-ajax.php with leadlovers-related actions from unauthenticated users
• Implement Web Application Firewall (WAF) rules to detect suspicious access patterns targeting the leadlovers forms plugin
• Review audit logs for unauthorized access attempts to form submission data or plugin configuration endpoints
• Use security plugins to track and alert on unusual API endpoint access patterns

Monitoring Recommendations

• Enable detailed logging for WordPress AJAX requests and REST API calls
• Set up alerts for access to leadlovers forms plugin endpoints without proper authentication headers
• Regularly review access logs for patterns consistent with automated scanning or exploitation attempts
• Monitor for bulk data access requests that may indicate data exfiltration attempts

How to Mitigate CVE-2026-39657

Immediate Actions Required

• Update the leadlovers forms plugin to a patched version as soon as one becomes available
• Disable the leadlovers forms plugin if it is not actively required until a patch is released
• Implement additional access controls at the web server or WAF level to restrict access to plugin endpoints
• Review audit logs for any signs of prior exploitation or unauthorized access

Patch Information

Check the Patchstack Vulnerability Advisory for the latest information on available patches and vendor response. Users should upgrade to a version higher than 1.0.2 when a patched release becomes available.

Workarounds

• Temporarily deactivate the leadlovers forms plugin until a security patch is released
• Implement IP-based access restrictions for WordPress admin and AJAX endpoints if feasible
• Use a Web Application Firewall (WAF) to block suspicious requests targeting the plugin
• Consider using WordPress security plugins that can add additional authorization layers

# Apache .htaccess workaround to restrict access to AJAX handlers
# Add to your WordPress root .htaccess file
<Files admin-ajax.php>
    <RequireAny>
        Require ip 192.168.1.0/24
        Require valid-user
    </RequireAny>
</Files>