Ai Image Alt Text Generator for WP <= 1.1.9 - Missing Authorization

This exploitation research plan targets CVE-2026-24579, a missing authorization vulnerability in the "Ai Image Alt Text Generator for WP" plugin.

1. Vulnerability Summary

The "Ai Image Alt Text Generator for WP" plugin (versions <= 1.1.9) fails to implement proper capability checks on one or more of its AJAX handlers registered via wp_ajax_*. While these handlers are protected against unauthenticated users (by lack of wp_ajax_nopriv_*), they do not verify if the logged-in user has the administrative privileges required to generate AI content or modify media metadata. This allows any authenticated user, including those with the subscriber role, to trigger unauthorized actions.

2. Attack Vector Analysis

• Endpoint: /wp-admin/admin-ajax.php
• HTTP Method: POST
• Authentication: Subscriber-level credentials (required).
• Vulnerable Action (Inferred): Likely ai_image_alt_text_generator_generate, ai_alt_text_process, or similar.
• Parameters:
  • action: The specific AJAX action (to be identified in Step 1 of the strategy).
  • nonce: A CSRF token (usually verified, but accessible to subscribers).
  • image_id / attachment_id: The ID of the image to process.
• Preconditions:
  • The plugin must be active.
  • A subscriber account must be created.
  • (Optional) An API key for the AI service might need to be configured in the plugin settings for the action to succeed, although the vulnerability exists regardless of the backend response.

3. Code Flow

1. Registration: The plugin registers an AJAX action during init or admin_init.
   • Code Pattern: add_action( 'wp_ajax_IMAGE_ACTION_NAME', [ $this, 'vulnerable_callback' ] );
2. Trigger: A subscriber sends a POST request to admin-ajax.php with action=IMAGE_ACTION_NAME.
3. Authentication: WordPress core verifies the user is logged in.
4. Verification (Weak): The callback likely calls check_ajax_referer( 'nonce_name', 'nonce_param' ). Because the nonce is often localized for all admin users (including subscribers accessing admin-ajax.php context), the subscriber can provide a valid nonce.
5. Missing Authorization: The callback function fails to call current_user_can( 'manage_options' ) or current_user_can( 'edit_posts' ).
6. Execution: The plugin proceeds to call an external AI API and updates the _wp_attachment_image_alt metadata for the specified attachment.

4. Nonce Acquisition Strategy

The plugin likely enqueues a script that localizes the nonce for use in the Media Library or the plugin's own settings page.

1. Identify Nonce Source: Search the plugin code for wp_localize_script.
   • Search Pattern: grep -r "wp_localize_script" .
2. Target Variable: Look for the object name and key (e.g., ai_alt_text_obj.nonce (inferred)).
3. Extraction:
   • Create a page or navigate to an admin area where the plugin's script is loaded.
   • Use browser_navigate to go to /wp-admin/upload.php (Media Library) as the subscriber.
   • Use browser_eval to extract the nonce:

     // Example (adjust based on real variable name found in grep)
     window.ai_image_alt_text_params?.nonce || window.ai_alt_text_data?.nonce
     

5. Exploitation Strategy

1. Discovery: Use grep on the plugin source to find all wp_ajax_ registrations.

   grep -rn "wp_ajax_" .
   

2. Analyze Callback: Examine the identified callback function for the absence of current_user_can().
3. Prepare Payload:
   • action: The identifier found in step 1.
   • nonce: Extracted via browser_eval.
   • attachment_id: An existing image ID.
4. Execute Attack: Use http_request to send the unauthorized command.
   • URL: http://localhost:8080/wp-admin/admin-ajax.php
   • Method: POST
   • Headers: Content-Type: application/x-www-form-urlencoded
   • Body: action=IDENTIFIED_ACTION&nonce=EXTRACTED_NONCE&attachment_id=IMAGE_ID

6. Test Data Setup

1. Install Plugin: Ensure ai-image-alt-text-generator-for-wp v1.1.9 is installed and active.
2. Create Image: Upload a sample image and note its Attachment ID.

   wp media import /path/to/image.jpg --title="Test Image"
   

3. Create Subscriber:

   wp user create attacker attacker@example.com --role=subscriber --user_pass=password123
   

4. Set "Alt Text" to empty: Ensure the image currently has no alt text.

   wp post term set <ID> "" --field=alt
   

7. Expected Results

• The admin-ajax.php request returns a 200 OK status with a success message (e.g., {"success":true,"data":"Alt text updated"}).
• The plugin interacts with its AI provider or local logic to generate text, despite the requester being only a subscriber.
• The database record for the attachment's alt text is modified.

8. Verification Steps

1. Check Meta: Use WP-CLI to verify the _wp_attachment_image_alt meta key has been updated for the target image.

   wp post meta get <IMAGE_ID> _wp_attachment_image_alt
   

2. Confirm Change: Compare the value before and after the exploit. If the value changed from empty (or the previous value) to a new AI-generated string, the authorization bypass is confirmed.

9. Alternative Approaches

• Bulk Action Endpoint: If the single image generation is secure, check for bulk processing handlers (e.g., ai_bulk_generate). These often reside in separate admin-only logic that might also miss capability checks.
• Settings Modification: Check if there's an AJAX action to save the AI API key or other plugin settings. If current_user_can is missing there, a subscriber could potentially change the API key to their own or delete it, causing a Denial of Service.
• Referer Bypass: If check_ajax_referer is used with the third parameter set to false and the result isn't checked:

  check_ajax_referer( 'action', 'nonce', false ); // Returns false on failure but continues
  

  In this case, the exploit can be performed without any nonce at all.