Generate new FormKey and replace for oldRequestParams

Author: osrecio

app/code/Magento/Customer/Model/Plugin/CustomerFlushFormKey.php

@@ -0,0 +1,52 @@
+<?php
+/**
+ * Copyright © 2013-2017 Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Customer\Model\Plugin;
+
+use Magento\Customer\Model\Session;
+use Magento\Framework\Data\Form\FormKey as DataFormKey;
+use Magento\PageCache\Observer\FlushFormKey;
+
+class CustomerFlushFormKey
+{
+    /**
+     * @var Session
+     */
+    private $session;
+
+    /**
+     * @var DataFormKey
+     */
+    private $dataFormKey;
+
+    /**
+     * Initialize dependencies.
+     *
+     * @param Session $session
+     * @param DataFormKey $dataFormKey
+     */
+    public function __construct(Session $session, DataFormKey $dataFormKey)
+    {
+        $this->session = $session;
+        $this->dataFormKey = $dataFormKey;
+    }
+
+    /**
+     * @param FlushFormKey $subject
+     * @param callable $proceed
+     * @param array $args
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function aroundExecute(FlushFormKey $subject, callable $proceed, ...$args)
+    {
+        $currentFormKey = $this->dataFormKey->getFormKey();
+        $proceed(...$args);
+        $beforeParams = $this->session->getBeforeRequestParams();
+        if ($beforeParams['form_key'] == $currentFormKey) {
+            $beforeParams['form_key'] = $this->dataFormKey->getFormKey();
+            $this->session->setBeforeRequestParams($beforeParams);
+        }
+    }
+}

app/code/Magento/Customer/etc/di.xml

@@ -313,6 +313,9 @@
     <type name="Magento\Framework\App\Action\AbstractAction">
         <plugin name="customerNotification" type="Magento\Customer\Model\Plugin\CustomerNotification"/>
     </type>
+    <type name="Magento\PageCache\Observer\FlushFormKey">
+        <plugin name="customerFlushFormKey" type="Magento\Customer\Model\Plugin\CustomerFlushFormKey"/>
+    </type>
     <type name="Magento\Customer\Model\Customer\NotificationStorage">
         <arguments>
             <argument name="cache" xsi:type="object">Magento\Customer\Model\Cache\Type\Notification</argument>