Exploitation Research Plan: CVE-2026-24991 (Extensions For CF7 IDOR)

1. Vulnerability Summary

The Extensions For CF7 plugin (versions <= 3.4.0) contains an Insecure Direct Object Reference (IDOR) vulnerability in its administrative AJAX handlers. Specifically, the function responsible for deleting stored contact form submissions (database entries) fails to perform a capability check (e.g., current_user_can('manage_options')) before executing the deletion. While it does verify a WordPress nonce, the nonce is enqueued in the admin dashboard for all authenticated users with access to wp-admin, including Contributors. This allows a Contributor-level attacker to delete any form submission by targeting its database ID.

2. Attack Vector Analysis

• Endpoint: /wp-admin/admin-ajax.php
• Action: vscf7_delete_data (inferred from plugin function naming conventions and similar CF7 database extensions).
• Vulnerable Parameter: id (the database ID of the submission to be deleted).
• Authentication Level: Contributor or higher.
• Preconditions:
  1. The "Contact Form 7 Database" feature must be active.
  2. At least one form submission must exist in the database.
  3. The attacker must have a valid session as a Contributor.

3. Code Flow

1. The plugin registers the AJAX action in the admin class (likely includes/admin/class-vscf7-admin.php or includes/class-vscf7-db.php):
   add_action( 'wp_ajax_vscf7_delete_data', array( $this, 'vscf7_delete_data' ) );
2. The vscf7_delete_data function is reached.
3. The code calls check_ajax_referer( 'vscf7_nonce', 'security' ); to verify the CSRF token.
4. Vulnerability: The code proceeds directly to $wpdb->delete() using the id provided in $_POST['id'] without verifying if the current user has the manage_options capability or owns the form.
5. The record is deleted from the {prefix}vscf7_submissions table (or similar).

4. Nonce Acquisition Strategy

The plugin localizes its admin scripts and nonces for use in the dashboard.

1. Identify Enqueue: The script vscf7-admin-script (inferred) is enqueued during admin_enqueue_scripts.
2. Access: A Contributor user can log into /wp-admin/index.php.
3. Extraction: The nonce is stored in a global JavaScript object, likely vscf_vars or vscf7_vars.
4. Command: Use browser_eval to extract the nonce:
   browser_eval("window.vscf_vars?.vscf7_nonce") (or window.vscf7_vars?.nonce).

5. Exploitation Strategy

Step 1: Discover Target ID

The attacker can guess IDs (starting from 1) or observe them if they have any access to the database list. For the PoC, we will identify a valid ID via WP-CLI.

Step 2: Extract Nonce

Navigate to the WordPress dashboard as a Contributor and extract the vscf7_nonce.

Step 3: Perform Deletion

Send a POST request to admin-ajax.php.

HTTP Request:

• URL: http://localhost:8080/wp-admin/admin-ajax.php
• Method: POST
• Headers: Content-Type: application/x-www-form-urlencoded
• Body:

  action=vscf7_delete_data&id=1&security=[NONCE_VALUE]
  

Step 4: Expected Response

• Status Code: 200 OK
• Response Body: 1 or a JSON success message (e.g., {"success":true}).

6. Test Data Setup

1. Install Plugins: Install contact-form-7 and extensions-for-cf7 (v3.4.0).
2. Create Form: Create a basic Contact Form 7 form.
3. Generate Data: Perform a frontend submission of the form to populate the database.
4. Create User: Create a user with the contributor role.
5. Identify ID: Check the database to find the ID of the new submission:
   wp db query "SELECT id FROM wp_vscf7_submissions LIMIT 1;" (Note: Table name may vary; check {prefix}vscf7_submissions).

7. Expected Results

• The HTTP request will return a successful status code.
• The database record corresponding to the targeted id will be permanently removed.
• The plugin will not block the request despite the user being only a Contributor.

8. Verification Steps

1. Check Database: Run a WP-CLI query to verify the record is gone:
   wp db query "SELECT count(*) FROM wp_vscf7_submissions WHERE id = 1;"
2. Confirm Role: Verify the user used for the exploit only has the Contributor role:
   wp user get [USERNAME] --field=roles

9. Alternative Approaches

• Action Name Variation: If vscf7_delete_data is incorrect, search for wp_ajax_vscf7 in the plugin directory to find the exact deletion hook (e.g., vscf7_delete_submission, vscf7_delete_db_row).
• Form Deletion: If the IDOR applies to form settings instead of database entries, look for the action vscf7_delete_form_settings and target the CF7 Form ID.
• Bulk Deletion: Check if vscf7_bulk_delete_data exists, which might accept an array of IDs in $_POST['ids'].