Popping Sidebars and Widgets Light <= 1.27 - Authenticated (Administrator+) Stored Cross-Site Scripting

This exploitation research plan focuses on CVE-2025-69007, a Stored Cross-Site Scripting (XSS) vulnerability in the "Popping Sidebars and Widgets Light" plugin.

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1. Vulnerability Summary

The "Popping Sidebars and Widgets Light" plugin (versions <= 1.27) fails to sufficiently sanitize and escape user-supplied configuration data for sidebars and widgets. While typically Administrators have the unfiltered_html capability (allowing them to post script tags intentionally), this vulnerability becomes critical in WordPress Multisite environments or installations where unfiltered_html has been disabled for Administrators. An attacker with Administrator privileges can inject malicious scripts into sidebar configurations, which are then stored in the database and executed whenever a user views a page containing that sidebar.

2. Attack Vector Analysis

• Endpoint: WordPress Admin Dashboard, specifically the plugin's settings or "Sidebars" management page.
• Vulnerable Action: Saving/Updating a sidebar's properties (likely via a POST request to wp-admin/admin.php or an AJAX call to admin-ajax.php).
• Parameter: Typically parameters like sidebar titles, custom CSS fields, or HTML content areas (e.g., sidebar_title, custom_css, content).
• Authentication: Administrator-level access is required.
• Precondition: The constant DISALLOW_UNFILTERED_HTML must be set to true in wp-config.php, or the site must be a Multisite installation where the user is a standard Administrator (not a Super Admin).

3. Code Flow (Inferred)

1. Entry Point: The plugin registers a menu page via add_menu_page() or add_submenu_page() in the admin_menu hook.
2. Processing: When the "Save" button is clicked, a request is sent to a handler. This handler is likely registered via admin_init or a specific wp_ajax_ action.
3. Sink (Storage): The handler retrieves the POST data (e.g., $_POST['sidebar_content']) and saves it using update_option() or update_post_meta() without passing it through wp_kses() or sanitize_text_field().
4. Sink (Output): On the frontend, the plugin retrieves this value and renders it. The rendering code likely uses echo or print directly on the retrieved value without using esc_html(), esc_attr(), or wp_kses_post().

4. Nonce Acquisition Strategy

Since the exploit requires Administrator authentication, the automated agent must log in as an administrator.

1. Navigate to Plugin Page: Use browser_navigate to go to the "Popping Sidebars" management page (e.g., /wp-admin/admin.php?page=popping-sidebars-options).
2. Identify Nonce: The "Save" form will contain a hidden nonce field for CSRF protection.
3. Extraction:
   • Inspect the HTML for a field like <input type="hidden" id="_wpnonce" name="_wpnonce" value="..." />.
   • Alternatively, look for localized JS variables: browser_eval("window.paws_data?.nonce") (inferred prefix paws from plugin name).
   • The most reliable method is reading the DOM: browser_eval("document.querySelector('input[name=\"_wpnonce\"]')?.value").

5. Exploitation Strategy

Step 1: Environment Setup
Ensure the Administrator user does not have unfiltered_html (simulate a hardened or multisite environment).

Step 2: Authentication
Log in to the WordPress instance using Administrator credentials.

Step 3: Payload Injection
Send a POST request to the configuration handler.

• Tool: http_request
• URL: http://localhost:8080/wp-admin/admin.php?page=popping-sidebars-options (or the relevant AJAX endpoint).
• Method: POST
• Content-Type: application/x-www-form-urlencoded
• Parameters:
  • _wpnonce: [Extracted Nonce]
  • action: update (inferred)
  • sidebar_title: Test Sidebar <script>alert(document.domain)</script>
  • submit: Save Changes

Step 4: Triggering the XSS
Navigate to any frontend page where the "Popping Sidebar" is configured to appear (e.g., the homepage or a specific post).

6. Test Data Setup

1. Plugin Installation: Activate popping-sidebars-and-widgets-light.
2. Hardening: Add define( 'DISALLOW_UNFILTERED_HTML', true ); to wp-config.php.
3. User Creation: Create an Administrator user (if not already present).
4. Sidebar Creation: Create at least one sidebar using the plugin UI so that an ID exists to target for updates.

7. Expected Results

• The POST request should return a 302 redirect (indicating success) or a 200 OK with a "Settings Saved" message.
• When viewing the frontend, the browser should execute the JavaScript, resulting in an alert box showing the domain.
• Inspecting the page source should show the raw <script> tag within the sidebar's HTML structure.

8. Verification Steps

1. Database Check: Use WP-CLI to check if the script is stored in the options table:
   wp option get paws_sidebars_settings --format=json (inferred option name).
2. HTML Verification: Use http_request to fetch the homepage and grep for the payload:
   http_request(url="http://localhost:8080/", method="GET") -> Check if <script>alert is present and unescaped.

9. Alternative Approaches

• AJAX Endpoint: If the plugin uses AJAX to save settings, look for wp_ajax_paws_save_sidebar (inferred). The payload would then be sent to /wp-admin/admin-ajax.php.
• Custom Post Types: If sidebars are stored as Custom Post Types, the exploit would involve sending a request to /wp-admin/post.php with action=editpost and the XSS payload in a post_meta field.
• Bypass: If sidebar_title is sanitized, try injecting into "Custom CSS" fields or "Custom JS" fields (if the plugin provides them, as they often forget to wrap these in proper tags or sanitize the content).