Exploit for CVE-2026-39440

## https://sploitus.com/exploit?id=C722AC52-6CC8-5E71-9137-648F5EFABB2F
# CVE-2026-39440 FunnelForms Fix

> A drop-in WordPress plugin that blocks the vulnerable Demo Import handler in **FunnelForms Pro ≤ 3.8.1** to mitigate **Remote Code Execution (CVE-2026-39440, CVSS 9.9)**.

---

## The Vulnerability

| Field            | Value                                                                 |
|------------------|-----------------------------------------------------------------------|
| **CVE ID**       | [CVE-2026-39440](https://nvd.nist.gov/vuln/detail/CVE-2026-39440)     |
| **CVSS Score**   | 9.9 (Critical)                                                        |
| **Affected**     | FunnelForms Pro ≤ 3.8.1                                               |
| **Privileges**   | Low (Subscriber-level)                                                 |
| **Type**         | Code Injection → Remote Code Inclusion → RCE                          |
| **Patched?**     | No official vendor patch available yet                                |
| **Discovered by**| [3ele / Sebastian Weiss](https://patchstack.com/database/researchers/e24e309a-024a-42e0-8f49-5178ae2d7c73) |
| **Published**    | 21 Apr 2026 (Patchstack)                                              |

## Root Cause

The `af2_demoimport` AJAX handler (`admin/menu_ajax_functions/demoimport.php`) has two fatal flaws:

### 1. `unserialize()` on Attacker-Controlled Data

```php
$jsonFile = file_get_contents( $imp_exp_tmp_path . 'af2_export.txt' );
$toImport = unserialize( urldecode( $jsonFile ) );
```

A crafted ZIP file containing a malicious `af2_export.txt` triggers **PHP Object Injection** at deserialization — leading to full Remote Code Execution.

### 2. Path Traversal via `$_POST['filename']`

```php
$filename = $_POST['filename'];
$file = pathinfo( AF2_PLUGIN_DIR . '/demos/' . $locale . '/' . $filename . '.zip' );
```

No `basename()`, no whitelist. An attacker supplies `../../../uploads/evil` and pulls an arbitrary ZIP from outside the `demos/` directory.

### Missing Security Controls

- No nonce verification
- No capability check
- No input sanitization

An authenticated user with minimal (Subscriber) privileges can exploit this chain.

## Installation

### As a Regular Plugin (Recommended)

1. Download or clone this repository
2. Upload the `cve-2026-39440-funnelforms-fix` folder to `wp-content/plugins/`
3. Activate it in **Plugins → Installed Plugins**

### As an MU-Plugin (Alternative)

Copy `cve-2026-39440-fix.php` directly to `wp-content/mu-plugins/`. No activation needed — MU-Plugins load automatically.

## What This Plugin Does

| Action                              | Hook                        | Priority |
|-------------------------------------|-----------------------------|----------|
| Blocks AJAX handler                 | `wp_ajax_af2_demoimport`    | 1        |
| Removes admin submenu               | `admin_menu`                | 999      |
| Dequeues demoimport JS/CSS          | `admin_enqueue_scripts`     | 20       |

The vulnerable code path is **never executed**. `wp_send_json_error()` calls `wp_die()` internally, so the plugin's handler is never reached.

## Verification

After activation:

1. The **"Demo import"** menu item should no longer appear under Funnelforms
2. Any request to `admin-ajax.php?action=af2_demoimport` returns:
   ```json
   {
       "success": false,
       "data": { "message": "Demo import is temporarily disabled for security reasons (CVE-2026-39440)." }
   }
   ```

## When to Remove

This plugin can be deactivated and deleted once FunnelForms Pro releases an official patched version (> 3.8.1) that:

- Replaces `unserialize()` with `json_decode()` or implements a strict allowlist
- Sanitizes the `filename` parameter (`basename()`, allowlist of known demos)
- Adds nonce verification and capability checks

## Credits

- **Discovered & reported by**: [3ele / Sebastian Weiss](https://patchstack.com/database/researchers/e24e309a-024a-42e0-8f49-5178ae2d7c73)
- **Published via**: [Patchstack](https://patchstack.com/)

## License

[GPL v2 or later](https://www.gnu.org/licenses/gpl-2.0.html)