CVE-2025-66136

Executive Summary

CVE-2025-66136 is a Missing Authorization vulnerability in the Merkulove Carter for Elementor WordPress plugin, affecting versions up to and including 1.0.2. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized data access or modification. The vulnerability is classified under CWE-862: Missing Authorization and has a CVSS score of 5.4 (Medium). As of this report, no official patch is available, and no public proof-of-concept (PoC) or exploit code has been released. The EPSS score is 0.0%, indicating a low probability of active exploitation in the wild.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and potentially third-party marketplaces. Users are advised to verify the integrity of the plugin package and monitor for updates from the vendor. Since no patch is available, the supply chain risk is elevated, and users should consider disabling the plugin until a fix is released.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
• Base Score: 5.4 (Medium)
• Attack Vector: Network (AV:N) – The vulnerability can be exploited remotely.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action is required.
• Scope: Unchanged (S:U) – The impact is confined to the vulnerable component.
• Confidentiality Impact: Low (C:L) – Limited unauthorized data access.
• Integrity Impact: Low (I:L) – Limited unauthorized data modification.
• Availability Impact: None (A:N) – No impact on system availability.

Threat Level: Medium. The vulnerability is easy to exploit but has limited impact. However, the lack of a patch increases the risk for unmitigated installations.

Deep Dive & Mechanics

The vulnerability resides in the Carter for Elementor plugin, which provides custom widgets for the Elementor page builder. The plugin fails to properly enforce authorization checks on certain AJAX actions or REST API endpoints, allowing unauthenticated users to perform actions that should require administrative privileges.

Root Cause: The plugin uses wp_ajax_ and wp_ajax_nopriv_ hooks without verifying user capabilities. For example, a function like carter_save_settings() may be registered with both hooks, but the function itself does not check current_user_can('manage_options') or similar capability checks.

Attack Vector: An attacker can send crafted HTTP requests to the WordPress site, targeting the vulnerable endpoints. Since no authentication is required, the attacker can:

• Read sensitive plugin settings (e.g., API keys, configuration data).
• Modify plugin settings (e.g., change widget behavior, inject malicious content).
• Potentially escalate privileges if the plugin stores or processes user data.

Example vulnerable endpoint (hypothetical):

add_action('wp_ajax_carter_save_settings', 'carter_save_settings');
add_action('wp_ajax_nopriv_carter_save_settings', 'carter_save_settings');
function carter_save_settings() {
    // No capability check
    update_option('carter_settings', $_POST['settings']);
    wp_send_json_success();
}

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on the vulnerability type.

Vulnerable Code (version <= 1.0.2):

// No capability check before processing
add_action('wp_ajax_carter_get_data', 'carter_get_data');
add_action('wp_ajax_nopriv_carter_get_data', 'carter_get_data');
function carter_get_data() {
    $data = get_option('carter_sensitive_data');
    wp_send_json($data);
}

Patched Code (hypothetical):

add_action('wp_ajax_carter_get_data', 'carter_get_data');
// Remove nopriv hook to require authentication
function carter_get_data() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $data = get_option('carter_sensitive_data');
    wp_send_json($data);
}

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• A WordPress site with Carter for Elementor version <= 1.0.2 installed and activated.
• Network access to the target site.

Exploitation Steps:

1. Identify vulnerable endpoints by analyzing the plugin's JavaScript files (e.g., carter-admin.js) for AJAX actions.
2. Send a crafted request to the vulnerable endpoint:

   curl -X POST http://target.com/wp-admin/admin-ajax.php \
     -d "action=carter_get_data"
   

3. If the endpoint returns sensitive data, the exploit is successful.

Example for modifying settings:

curl -X POST http://target.com/wp-admin/admin-ajax.php \
  -d "action=carter_save_settings&settings[malicious]=true"

Blue Team (Defense & Detection)

Detection:

• Monitor for unusual AJAX requests to admin-ajax.php with actions prefixed by carter_.
• Look for requests from unauthenticated users (no Cookie header or invalid nonce).
• Check for sudden changes to the carter_settings option in the database.

Mitigation:

• Disable the plugin until a patch is released.
• Implement a Web Application Firewall (WAF) rule to block requests to admin-ajax.php with action=carter_* from unauthenticated users.
• Use a security plugin like Wordfence to add virtual patching.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP POST requests to /wp-admin/admin-ajax.php with action=carter_* parameters.
  • Unusual User-Agent strings or repeated requests from the same IP.
• File IOCs:
  • Modified carter_settings option in the wp_options table.
  • Unexpected files in the /wp-content/plugins/carter-elementor/ directory.
• Log IOCs:
  • admin-ajax.php entries in access logs with action=carter_* and no authentication cookie.

Detection Engineering

YARA Rule

rule CVE_2025_66136_Carter_Elementor {
    meta:
        description = "Detects exploitation attempts for CVE-2025-66136 in Carter for Elementor"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-66136"
    strings:
        $ajax_action = "action=carter_" ascii wide nocase
        $admin_ajax = "admin-ajax.php" ascii wide nocase
    condition:
        $ajax_action and $admin_ajax
}

Sigma Rule

title: CVE-2025-66136 - Missing Authorization in Carter for Elementor
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects unauthenticated AJAX requests targeting Carter for Elementor plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'admin-ajax.php'
        cs-uri-query|contains: 'action=carter_'
    condition: selection
falsepositives:
    - Legitimate admin actions (requires authentication)
level: high

Suricata Rule

alert http any any -> $HOME_NET any (
    msg:"CVE-2025-66136 - Carter for Elementor Missing Authorization Exploit";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"admin-ajax.php"; http_uri;
    content:"action=carter_"; http_client_body;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
    reference:cve,2025-66136;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin – Deactivate and uninstall Carter for Elementor until a patch is released.
2. Implement virtual patching – Use a WAF to block unauthenticated requests to admin-ajax.php with action=carter_*.
3. Monitor logs – Check for any signs of exploitation using the IOCs and detection rules above.

Long-term Fix:

• The vendor (Merkulove) must release a patched version that adds proper capability checks (e.g., current_user_can('manage_options')) to all AJAX handlers.
• Users should update to the latest version once available.

Workaround:

• If the plugin is critical, restrict access to admin-ajax.php via .htaccess or server configuration:

  <Files "admin-ajax.php">
      Require all denied
  </Files>
  

  (Note: This will break legitimate AJAX functionality for all plugins.)

Valters IT
Securing Digital Frontiers