SilentPost.php

<?php
/**
 *
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Magento\Paypal\Controller\Payflow;

use Magento\Framework\App\CsrfAwareActionInterface;
use Magento\Framework\App\Request\InvalidRequestException;
use Magento\Framework\App\RequestInterface;

class SilentPost extends \Magento\Paypal\Controller\Payflow implements CsrfAwareActionInterface
{
    /**
     * @inheritDoc
     */
    public function createCsrfValidationException(
        RequestInterface $request
    ): ?InvalidRequestException {
        return null;
    }

    /**
     * @inheritDoc
     */
    public function validateForCsrf(RequestInterface $request): ?bool
    {
        return true;
    }

    /**
     * Get response from PayPal by silent post method
     *
     * @return void
     */
    public function execute()
    {
        $data = $this->getRequest()->getPostValue();
        if (isset($data['INVNUM'])) {
            /** @var $paymentModel \Magento\Paypal\Model\Payflowlink */
            $paymentModel = $this->_payflowModelFactory->create();
            try {
                $paymentModel->process($data);
            } catch (\Exception $e) {
                $this->_logger->critical($e);
            }
        }
    }
}