CVE-2026-6451: WordPress CMS für Motorrad Plugin CSRF Flaw

CVE-2026-6451 Overview

The cms-fuer-motorrad-werkstaetten plugin for WordPress contains a Cross-Site Request Forgery (CSRF) vulnerability in versions up to and including 1.0.0. This specialized plugin, designed for motorcycle workshop management, exposes eight AJAX deletion handlers that lack proper security validation. The vulnerability allows unauthenticated attackers to delete critical business data including vehicles, contacts, suppliers, receipts, positions, catalog articles, stock items, and entire supplier catalogs through forged requests.

Critical Impact

Attackers can trick authenticated administrators into unknowingly deleting critical motorcycle workshop business data, potentially causing significant operational disruption and data loss.

Affected Products

• cms-fuer-motorrad-werkstaetten WordPress plugin versions ≤ 1.0.0
• WordPress installations with the vulnerable plugin active

Discovery Timeline

• 2026-04-17 - CVE-2026-6451 published to NVD
• 2026-04-22 - Last updated in NVD database

Technical Details for CVE-2026-6451

Vulnerability Analysis

This CSRF vulnerability stems from a complete absence of security controls on all eight AJAX deletion handlers within the plugin. The affected handlers include:

• vehicles_cfmw_d_vehicle - Deletes vehicle records
• contacts_cfmw_d_contact - Deletes contact information
• suppliers_cfmw_d_supplier - Deletes supplier records
• receipts_cfmw_d_receipt - Deletes receipt data
• positions_cfmw_d_position - Deletes position entries
• catalogs_cfmw_d_article - Deletes catalog articles
• stock_cfmw_d_item - Deletes stock inventory items
• settings_cfmw_d_catalog - Deletes entire supplier catalogs

None of these handlers implement check_ajax_referer() or wp_verify_nonce() for request validation, nor do they verify user capabilities via current_user_can(). This combination of missing security controls creates a direct path for exploitation.

Root Cause

The root cause is the complete omission of WordPress's built-in CSRF protection mechanisms. WordPress provides the check_ajax_referer() and wp_verify_nonce() functions specifically to validate that AJAX requests originate from legitimate sources within the WordPress admin interface. Additionally, the handlers fail to implement capability checks using current_user_can(), meaning even if a nonce were present, there would be no verification that the requesting user has appropriate permissions to perform deletion operations.

Attack Vector

The attack requires social engineering to succeed. An attacker must craft a malicious webpage containing hidden forms or JavaScript that automatically submit DELETE requests to the vulnerable AJAX endpoints. When an authenticated WordPress administrator visits this malicious page while logged into their WordPress site, the browser automatically includes their session cookies, causing the deletion requests to execute with the administrator's privileges.

The malicious page could be delivered through phishing emails, compromised websites, or malicious advertisements. Since the deletion operations are performed via POST requests to the WordPress admin-ajax.php endpoint, the attacker's payload simply needs to target the appropriate action parameter along with the ID of the record to delete.

For technical implementation details, refer to the Wordfence Vulnerability Analysis and the vulnerable source files in the WordPress Plugin Repository.

Detection Methods for CVE-2026-6451

Indicators of Compromise

• Unexpected deletion of vehicle records, contacts, suppliers, or other plugin-managed data
• Web server logs showing POST requests to /wp-admin/admin-ajax.php with CFMW deletion actions originating from external referrers
• Audit logs indicating bulk deletions occurring without corresponding admin panel activity

Detection Strategies

• Monitor Apache/Nginx access logs for POST requests to admin-ajax.php containing action parameters matching the pattern *_cfmw_d_*
• Implement referrer header validation alerts for AJAX requests originating from non-WordPress domains
• Enable WordPress audit logging to track deletion operations and correlate with admin user activity

Monitoring Recommendations

• Deploy a Web Application Firewall (WAF) rule to flag AJAX requests to sensitive CFMW endpoints lacking valid nonce parameters
• Configure SIEM alerts for unusual patterns of DELETE operations against plugin database tables
• Regularly backup plugin-managed data to enable recovery from potential CSRF attacks

How to Mitigate CVE-2026-6451

Immediate Actions Required

• Review the WordPress Plugin Repository for updated versions of cms-fuer-motorrad-werkstaetten that address this vulnerability
• Consider temporarily deactivating the plugin if it manages critical business data until a patch is available
• Implement additional CSRF protection at the web server or WAF level
• Educate administrative users about the risks of clicking unknown links while logged into WordPress

Patch Information

As of the last NVD update on 2026-04-22, check the WordPress Plugin Repository for the trunk version to determine if nonce validation has been implemented. The plugin should be updated to include check_ajax_referer() calls in all eight affected deletion handlers.

Workarounds

• Restrict administrative WordPress sessions to trusted networks only using IP-based access controls
• Implement a Content Security Policy (CSP) header that limits form submissions to same-origin requests
• Use browser isolation or separate browser profiles for WordPress administration

# Apache .htaccess configuration to restrict admin-ajax.php access
<Files "admin-ajax.php">
    Order Deny,Allow
    Deny from all
    Allow from 192.168.1.0/24
    Allow from 10.0.0.0/8
</Files>