Community Events <= 1.5.7 - Authenticated (Administrator+) Stored Cross-Site Scripting via 'ce_venue_name' Parameter

This research plan outlines the steps required to demonstrate the Stored Cross-Site Scripting (XSS) vulnerability in the Community Events plugin (CVE-2026-1649).

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1. Vulnerability Summary

• ID: CVE-2026-1649
• Vulnerability Type: Stored Cross-Site Scripting (XSS)
• Vulnerable Parameter: ce_venue_name
• Affected Versions: <= 1.5.7
• Description: The plugin fails to sanitize the ce_venue_name parameter during storage and fails to escape it upon output. While it requires Administrator-level privileges to inject, the resulting script executes in the context of any user (including other Administrators) viewing the venue list or associated event pages.

2. Attack Vector Analysis

• Endpoint: WordPress Admin Dashboard, specifically the Venue management or Settings page of the Community Events plugin.
• HTTP Method: POST
• Vulnerable Action: Saving or updating a venue. (Likely handled via a standard form submission to options.php or a custom admin-ajax.php action).
• Required Role: Administrator
• Payload Location: The ce_venue_name field within the POST request.

3. Code Flow (Inferred)

1. Entry Point: An administrator navigates to the "Venues" or "Add New Event" section of the Community Events plugin.
2. Input Handling: The plugin processes a POST request containing event/venue details. It retrieves the ce_venue_name parameter from $_POST.
3. Storage: The code likely calls update_option() or update_post_meta() (or a custom $wpdb->insert) without applying sanitize_text_field() to the venue name.
4. Output Sink: When the list of venues is rendered in the admin dashboard or on a frontend event submission form, the plugin retrieves the stored value and echos it directly without using esc_html() or esc_attr().

4. Nonce Acquisition Strategy

Since the vulnerability is authenticated (Admin+), the exploitation agent must first log in and then extract the necessary security nonces from the target page.

1. Identify the Page: Navigate to the Community Events venue management page (likely wp-admin/admin.php?page=community-events-venues or similar).
2. Extract Nonce:
   • Use browser_navigate to reach the settings/venue page.
   • Use browser_eval to search for nonce fields in the HTML or localized JS.
   • Common patterns:
     • document.querySelector('input[name="_wpnonce"]')?.value
     • document.querySelector('#ce_venue_nonce')?.value (inferred)
     • window.ce_admin_params?.nonce (inferred)

5. Exploitation Strategy

The goal is to inject a stored script into the venue name field.

Step 1: Setup Admin Session

• Log in to the WordPress instance as an administrator.

Step 2: Identify the Save Request

• Manually (or via the agent) create a dummy venue to observe the HTTP request structure.
• Target URL: /wp-admin/admin.php?page=community-events-venues (or the relevant plugin sub-page).

Step 3: Submit XSS Payload

• Payload: "><script>alert(document.domain)</script>
• HTTP Request (via http_request):

  POST /wp-admin/admin.php?page=community-events-venues HTTP/1.1
  Content-Type: application/x-www-form-urlencoded
  
  ce_venue_name=%22%3E%3Cscript%3Ealert%28document.domain%29%3C%2Fscript%3E&ce_venue_description=Test&submit=Save+Venue&_wpnonce=[EXTRACTED_NONCE]
  

Step 4: Trigger Execution

• Navigate to the venue list page: /wp-admin/admin.php?page=community-events-venues.
• Observe if the alert() executes.

6. Test Data Setup

1. Install Plugin: Ensure community-events version <= 1.5.7 is active.
2. User: Create an administrator user.
3. Content: If the plugin requires a "Location" or "Event" to be created first to access the venue name field, create a placeholder event.

7. Expected Results

• The POST request should return a 302 redirect or a 200 OK indicating success.
• When the admin page (or a frontend page displaying venues) is loaded, the raw HTML should contain the unescaped script: ce_venue_name" value=""><script>alert(document.domain)</script>.
• The browser should execute the JavaScript, resulting in an alert box.

8. Verification Steps

1. Check Database: Use WP-CLI to verify the stored value in the options or postmeta table.

   wp option get ce_venues --format=json # (Inferred option name)
   # OR if venues are post types:
   wp post list --post_type=ce_venue
   wp post meta list [POST_ID]
   

2. Verify Output: Use the http_request tool to fetch the venue list page and grep for the payload.

   # Look for the unescaped payload in the response body
   grep -a "><script>alert(document.domain)</script>" response_body.html
   

9. Alternative Approaches

• If the sink is in an attribute: If the XSS is inside an <input> value, use " onmouseover="alert(1) or " autofocus onfocus="alert(1).
• If the sink is in a frontend shortcode:
  1. Create a page: wp post create --post_type=page --post_title="Events" --post_content="[community_events_list]" (inferred shortcode).
  2. Visit the page as any user to verify the XSS triggers on the frontend.
• REST API: Check if the plugin registers a REST route for venue management (/wp-json/community-events/v1/venues) which might lack permission checks or sanitization.