A discovered vulnerability allows users to modify their shopping cart after completing the PayPal Checkout process and payment authorization. If a user initiates a PayPal transaction from a product page or the cart page and then returns to the order summary page, they can still manipulate the cart contents before finalizing the order. As a result, the order amount in Sylius may be higher than the amount actually captured by PayPal, leading to a scenario where merchants deliver products or services without full payment.
Impact
- Users can exploit this flaw to receive products/services without paying the full amount. - Merchants may suffer financial losses due to underpaid orders. - Trust in the integrity of the payment process is compromised.
Patches
The issue is fixed in versions: 1.6.2, 1.7.2, 2.0.2 and above.
Workarounds
To resolve the problem in the end application without updating to the newest patches, there is a need to overwrite PayPalOrderCompleteProcessor with modified logic:
php <?php
declare(stricttypes=1);
namespace App\Processor;
use Sylius\Bundle\PayumBundle\Model\GatewayConfigInterface; use Sylius\Component\Core\Model\OrderInterface; use Sylius\Component\Core\Model\PaymentInterface; use Sylius\Component\Core\Model\PaymentMethodInterface; use Sylius\PayPalPlugin\Manager\PaymentStateManagerInterface;
final class PayPalOrderCompleteProcessor { public function construct(private readonly PaymentStateManagerInterface $paymentStateManager) { }
public function completePayPalOrder(OrderInterface $order): void { $payment = $order->getLastPayment(PaymentInterface::STATEPROCESSING); if ($payment === null) { return; }
/ @var PaymentMethodInterface $paymentMethod / $paymentMethod = $payment->getMethod(); / @var GatewayConfigInterface $gatewayConfig / $gatewayConfig = $paymentMethod->getGatewayConfig();
if ($gatewayConfig->getFactoryName() !== 'sylius.paypal') { return; }
try { $this->verify($payment); } catch (\Exception) { $this->paymentStateManager->cancel($payment);
return; }
$this->paymentStateManager->complete($payment); }
private function verify(PaymentInterface $payment): void { $totalAmount = $this->getTotalPaymentAmountFromPaypal($payment);
if ($payment->getOrder()->getTotal() !== $totalAmount) { throw new \Exception(); } }
private function getTotalPaymentAmountFromPaypal(PaymentInterface $payment): int { $details = $payment->getDetails();
return $details['paymentamount'] ?? 0; } }
IMPORTANT
For PayPalPlugin 2.x change: php $gatewayConfig->getFactoryName() !== 'sylius.paypal' to php $gatewayConfig->getFactoryName() !== SyliusPayPalExtension::PAYPALFACTORYNAME
Also there is a need to overwrite CompletePayPalOrderListener with modified logic:
php <?php
declare(stricttypes=1);
namespace App\EventListener\Workflow;
use App\Processor\PayPalOrderCompleteProcessor; use Sylius\Component\Core\Model\OrderInterface; use Symfony\Component\Workflow\Event\CompletedEvent; use Webmozart\Assert\Assert;
final class CompletePayPalOrderListener { public function construct(private readonly PayPalOrderCompleteProcessor $completeProcessor) { }
public function invoke(CompletedEvent $event): void { / @var OrderInterface $order / $order = $event->getSubject(); Assert::isInstanceOf($order, OrderInterface::class);
$this->completeProcessor->completePayPalOrder($order); } }
And to overwrite CaptureAction with modified logic (if you didn't have it already):
php <?php
declare(stricttypes=1);
namespace App\Payum\Action;
use Payum\Core\Action\ActionInterface; use Payum\Core\Exception\RequestNotSupportedException; use Payum\Core\Request\Capture; use Sylius\Component\Core\Model\PaymentInterface; use Sylius\Component\Core\Model\PaymentMethodInterface; use Sylius\PayPalPlugin\Api\CacheAuthorizeClientApiInterface; use Sylius\PayPalPlugin\Api\CreateOrderApiInterface; use Sylius\PayPalPlugin\Payum\Action\StatusAction; use Sylius\PayPalPlugin\Provider\UuidProviderInterface;
final class CaptureAction implements ActionInterface { public function construct( private CacheAuthorizeClientApiInterface $authorizeClientApi, private CreateOrderApiInterface $createOrderApi, private UuidProviderInterface $uuidProvider, ) { }
/ @param Capture $request / public function execute($request): void { RequestNotSupportedException::assertSupports($this, $request);
/ @var PaymentInterface $payment / $payment = $request->getModel(); / @var PaymentMethodInterface $paymentMethod / $paymentMethod = $payment->getMethod();
$token = $this->authorizeClientApi->authorize($paymentMethod);
$referenceId = $this->uuidProvider->provide(); $content = $this->createOrderApi->create($token, $payment, $referenceId);
if ($content['status'] === 'CREATED') { $payment->setDetails([ 'status' => StatusAction::STATUSCAPTURED, 'paypalorderid' => $content['id'], 'referenceid' => $referenceId, 'paymentamount' => $payment->getAmount(), ]); } }
public function supports($request): bool { return $request instanceof Capture && $request->getModel() instanceof PaymentInterface ; } }
After that, register services in the container when using PayPal 1.x:
yaml Sylius\PayPalPlugin\EventListener\Workflow\CompletePayPalOrderListener: class: App\EventListener\Workflow\CompletePayPalOrderListener public: true arguments: - '@Sylius\PayPalPlugin\Processor\PayPalOrderCompleteProcessor' tags: - { name: 'kernel.eventlistener', event: 'workflow.syliusordercheckout.completed.complete', priority: 100 } Sylius\PayPalPlugin\Processor\PayPalOrderCompleteProcessor: class: App\Processor\PayPalOrderCompleteProcessor public: true arguments: - '@Sylius\PayPalPlugin\Manager\PaymentStateManagerInterface'
Sylius\PayPalPlugin\Payum\Action\CaptureAction: class: App\Payum\Action\CaptureAction public: true arguments: - '@Sylius\PayPalPlugin\Api\CacheAuthorizeClientApiInterface' - '@Sylius\PayPalPlugin\Api\CreateOrderApiInterface' - '@Sylius\PayPalPlugin\Provider\UuidProviderInterface' tags: - { name: 'payum.action', factory: 'sylius.paypal', alias: 'payum.action.capture' }
or when using PayPal 2.x:
yaml syliuspaypal.listener.workflow.completepaypalorder: class: App\EventListener\Workflow\CompletePayPalOrderListener public: true arguments: - '@syliuspaypal.processor.paypalordercomplete' tags: - { name: 'kernel.eventlistener', event: 'workflow.syliusordercheckout.completed.complete', priority: 100 } syliuspaypal.processor.paypalordercomplete: class: App\Processor\PayPalOrderCompleteProcessor public: true arguments: - '@syliuspaypal.manager.paymentstate'
syliuspaypal.payum.action.capture: class: App\Payum\Action\CaptureAction public: true arguments: - '@syliuspaypal.api.cacheauthorizeclient' - '@syliuspaypal.api.createorder' - '@syliuspaypal.provider.uuid' tags: - { name: 'payum.action', factory: 'sylius.paypal', alias: 'payum.action.capture' }
For more information
If you have any questions or comments about this advisory: Open an issue in Sylius issues Email us at security@sylius.com
A vulnerability allows users to manipulate the final payment amount processed by PayPal. If a user modifies the item quantity in their shopping cart after initiating the PayPal Checkout process, PayPal will not receive the updated total amount. As a result, PayPal captures only the initially transmitted amount, while Sylius incorrectly considers the order fully paid based on the modified total. This flaw can be exploited both accidentally and intentionally, potentially enabling fraud by allowing customers to pay less than the actual order value.
Impact
- Attackers can intentionally pay less than the actual total order amount. - Business owners may suffer financial losses due to underpaid orders. - Integrity of payment processing is compromised.
Patches
The issue is fixed in versions: 1.6.1, 1.7.1, 2.0.1 and above.
Workarounds
To resolve the problem in the end application without updating to the newest patches, there is a need to overwrite ProcessPayPalOrderAction with modified logic:
php <?php
declare(stricttypes=1);
namespace App\Controller;
use Doctrine\Persistence\ObjectManager; use SM\Factory\FactoryInterface as StateMachineFactoryInterface; use Sylius\Abstraction\StateMachine\StateMachineInterface; use Sylius\Abstraction\StateMachine\WinzouStateMachineAdapter; use Sylius\Component\Core\Factory\AddressFactoryInterface; use Sylius\Component\Core\Model\CustomerInterface; use Sylius\Component\Core\Model\PaymentInterface; use Sylius\Component\Core\Model\PaymentMethodInterface; use Sylius\Component\Core\OrderCheckoutTransitions; use Sylius\Component\Core\Repository\CustomerRepositoryInterface; use Sylius\Component\Resource\Factory\FactoryInterface; use Sylius\PayPalPlugin\Api\CacheAuthorizeClientApiInterface; use Sylius\PayPalPlugin\Api\OrderDetailsApiInterface; use Sylius\PayPalPlugin\Manager\PaymentStateManagerInterface; use Sylius\PayPalPlugin\Provider\OrderProviderInterface; use Sylius\PayPalPlugin\Verifier\PaymentAmountVerifierInterface; use Symfony\Component\HttpFoundation\JsonResponse; use Symfony\Component\HttpFoundation\Request; use Symfony\Component\HttpFoundation\Response;
final class ProcessPayPalOrderAction { public function construct( private readonly CustomerRepositoryInterface $customerRepository, private readonly FactoryInterface $customerFactory, private readonly AddressFactoryInterface $addressFactory, private readonly ObjectManager $orderManager, private readonly StateMachineFactoryInterface|StateMachineInterface $stateMachineFactory, private readonly PaymentStateManagerInterface $paymentStateManager, private readonly CacheAuthorizeClientApiInterface $authorizeClientApi, private readonly OrderDetailsApiInterface $orderDetailsApi, private readonly OrderProviderInterface $orderProvider, ) { }
public function invoke(Request $request): Response { $orderId = $request->request->getInt('orderId'); $order = $this->orderProvider->provideOrderById($orderId); / @var PaymentInterface $payment / $payment = $order->getLastPayment(PaymentInterface::STATECART);
$data = $this->getOrderDetails((string) $request->request->get('payPalOrderId'), $payment);
/ @var CustomerInterface|null $customer / $customer = $order->getCustomer(); if ($customer === null) { $customer = $this->getOrderCustomer($data['payer']); $order->setCustomer($customer); }
$purchaseUnit = (array) $data['purchaseunits'][0];
$address = $this->addressFactory->createNew();
if ($order->isShippingRequired()) { $name = explode(' ', $purchaseUnit['shipping']['name']['fullname']); $address->setLastName(arraypop($name) ?? ''); $address->setFirstName(implode(' ', $name)); $address->setStreet($purchaseUnit['shipping']['address']['addressline1']); $address->setCity($purchaseUnit['shipping']['address']['adminarea2']); $address->setPostcode($purchaseUnit['shipping']['address']['postalcode']); $address->setCountryCode($purchaseUnit['shipping']['address']['countrycode']);
$this->getStateMachine()->apply($order, OrderCheckoutTransitions::GRAPH, OrderCheckoutTransitions::TRANSITIONADDRESS); $this->getStateMachine()->apply($order, OrderCheckoutTransitions::GRAPH, OrderCheckoutTransitions::TRANSITIONSELECTSHIPPING); } else { $address->setFirstName($customer->getFirstName()); $address->setLastName($customer->getLastName());
$defaultAddress = $customer->getDefaultAddress();
$address->setStreet($defaultAddress ? $defaultAddress->getStreet() : ''); $address->setCity($defaultAddress ? $defaultAddress->getCity() : ''); $address->setPostcode($defaultAddress ? $defaultAddress->getPostcode() : ''); $address->setCountryCode($data['payer']['address']['countrycode']);
$this->getStateMachine()->apply($order, OrderCheckoutTransitions::GRAPH, OrderCheckoutTransitions::TRANSITIONADDRESS); }
$order->setShippingAddress(clone $address); $order->setBillingAddress(clone $address);
$this->getStateMachine()->apply($order, OrderCheckoutTransitions::GRAPH, OrderCheckoutTransitions::TRANSITIONSELECTPAYMENT);
$this->orderManager->flush();
try { $this->verify($payment, $data); } catch (\Exception) { $this->paymentStateManager->cancel($payment);
return new JsonResponse(['orderID' => $order->getId()]); }
$this->paymentStateManager->create($payment); $this->paymentStateManager->process($payment);
return new JsonResponse(['orderID' => $order->getId()]); }
private function getOrderCustomer(array $customerData): CustomerInterface { / @var CustomerInterface|null $existingCustomer / $existingCustomer = $this->customerRepository->findOneBy(['email' => $customerData['emailaddress']]); if ($existingCustomer !== null) { return $existingCustomer; }
/ @var CustomerInterface $customer / $customer = $this->customerFactory->createNew(); $customer->setEmail($customerData['emailaddress']); $customer->setFirstName($customerData['name']['givenname']); $customer->setLastName($customerData['name']['surname']);
return $customer; }
private function getOrderDetails(string $id, PaymentInterface $payment): array { / @var PaymentMethodInterface $paymentMethod / $paymentMethod = $payment->getMethod(); $token = $this->authorizeClientApi->authorize($paymentMethod);
return $this->orderDetailsApi->get($token, $id); }
private function getStateMachine(): StateMachineInterface { if ($this->stateMachineFactory instanceof StateMachineFactoryInterface) { return new WinzouStateMachineAdapter($this->stateMachineFactory); }
return $this->stateMachineFactory; }
private function verify(PaymentInterface $payment, array $paypalOrderDetails): void { $totalAmount = $this->getTotalPaymentAmountFromPaypal($paypalOrderDetails);
if ($payment->getAmount() !== $totalAmount) { throw new \Exception(); } }
private function getTotalPaymentAmountFromPaypal(array $paypalOrderDetails): int { if (!isset($paypalOrderDetails['purchaseunits']) || !isarray($paypalOrderDetails['purchaseunits'])) { return 0; }
$totalAmount = 0;
foreach ($paypalOrderDetails['purchaseunits'] as $unit) { $stringAmount = $unit['amount']['value'] ?? '0';
$totalAmount += (int) ($stringAmount 100); }
return $totalAmount; } }
Also there is a need to overwrite CompletePayPalOrderFromPaymentPageAction with modified logic:
php <?php
declare(stricttypes=1);
namespace App\Controller;
use Doctrine\Persistence\ObjectManager; use SM\Factory\FactoryInterface; use Sylius\Abstraction\StateMachine\StateMachineInterface; use Sylius\Abstraction\StateMachine\WinzouStateMachineAdapter; use Sylius\Component\Core\Model\PaymentInterface; use Sylius\Component\Core\OrderCheckoutTransitions; use Sylius\Component\Order\Processor\OrderProcessorInterface; use Sylius\PayPalPlugin\Exception\PaymentAmountMismatchException; use Sylius\PayPalPlugin\Manager\PaymentStateManagerInterface; use Sylius\PayPalPlugin\Provider\OrderProviderInterface; use Sylius\PayPalPlugin\Verifier\PaymentAmountVerifierInterface; use Symfony\Component\HttpFoundation\JsonResponse; use Symfony\Component\HttpFoundation\Request; use Symfony\Component\HttpFoundation\Response; use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
final class CompletePayPalOrderFromPaymentPageAction { public function construct( private readonly PaymentStateManagerInterface $paymentStateManager, private readonly UrlGeneratorInterface $router, private readonly OrderProviderInterface $orderProvider, private readonly FactoryInterface|StateMachineInterface $stateMachine, private readonly ObjectManager $orderManager, private readonly OrderProcessorInterface $orderProcessor, ) { }
public function invoke(Request $request): Response { $orderId = $request->attributes->getInt('id');
$order = $this->orderProvider->provideOrderById($orderId); / @var PaymentInterface $payment / $payment = $order->getLastPayment(PaymentInterface::STATEPROCESSING);
try { $this->verify($payment); } catch (\Exception) { $this->paymentStateManager->cancel($payment); $order->removePayment($payment);
$this->orderProcessor->process($order);
return new JsonResponse([ 'returnurl' => $this->router->generate('syliusshopcheckoutcomplete', [], UrlGeneratorInterface::ABSOLUTEURL), ]); }
$this->paymentStateManager->complete($payment);
$this->getStateMachine()->apply($order, OrderCheckoutTransitions::GRAPH, OrderCheckoutTransitions::TRANSITIONSELECTPAYMENT); $this->getStateMachine()->apply($order, OrderCheckoutTransitions::GRAPH, OrderCheckoutTransitions::TRANSITIONCOMPLETE);
$this->orderManager->flush();
$request->getSession()->set('syliusorderid', $order->getId());
return new JsonResponse([ 'returnurl' => $this->router->generate('syliusshoporderthankyou', [], UrlGeneratorInterface::ABSOLUTEURL), ]); }
private function getStateMachine(): StateMachineInterface { if ($this->stateMachine instanceof FactoryInterface) { return new WinzouStateMachineAdapter($this->stateMachine); }
return $this->stateMachine; }
private function verify(PaymentInterface $payment): void { $totalAmount = $this->getTotalPaymentAmountFromPaypal($payment);
if ($payment->getOrder()->getTotal() !== $totalAmount) { throw new \Exception(); } }
private function getTotalPaymentAmountFromPaypal(PaymentInterface $payment): int { $details = $payment->getDetails();
return $details['paymentamount'] ?? 0; } }
And to overwrite CaptureAction with modified logic:
php <?php
declare(stricttypes=1);
namespace App\Payum\Action;
use Payum\Core\Action\ActionInterface; use Payum\Core\Exception\RequestNotSupportedException; use Payum\Core\Request\Capture; use Sylius\Component\Core\Model\PaymentInterface; use Sylius\Component\Core\Model\PaymentMethodInterface; use Sylius\PayPalPlugin\Api\CacheAuthorizeClientApiInterface; use Sylius\PayPalPlugin\Api\CreateOrderApiInterface; use Sylius\PayPalPlugin\Payum\Action\StatusAction; use Sylius\PayPalPlugin\Provider\UuidProviderInterface;
final class CaptureAction implements ActionInterface { public function construct( private CacheAuthorizeClientApiInterface $authorizeClientApi, private CreateOrderApiInterface $createOrderApi, private UuidProviderInterface $uuidProvider, ) { }
/ @param Capture $request / public function execute($request): void { RequestNotSupportedException::assertSupports($this, $request);
/ @var PaymentInterface $payment / $payment = $request->getModel(); / @var PaymentMethodInterface $paymentMethod / $paymentMethod = $payment->getMethod();
$token = $this->authorizeClientApi->authorize($paymentMethod);
$referenceId = $this->uuidProvider->provide(); $content = $this->createOrderApi->create($token, $payment, $referenceId);
if ($content['status'] === 'CREATED') { $payment->setDetails([ 'status' => StatusAction::STATUSCAPTURED, 'paypalorderid' => $content['id'], 'referenceid' => $referenceId, 'paymentamount' => $payment->getAmount(), ]); } }
public function supports($request): bool { return $request instanceof Capture && $request->getModel() instanceof PaymentInterface ; } }
After that, register services in the container when using PayPal 1.x:
yaml services: App\Controller\ProcessPayPalOrderAction: class: App\Controller\ProcessPayPalOrderAction public: true arguments: - '@sylius.repository.customer' - '@sylius.factory.customer' - '@sylius.factory.address' - '@sylius.manager.order' - '@syliusabstraction.statemachine' - '@Sylius\PayPalPlugin\Manager\PaymentStateManagerInterface' - '@Sylius\PayPalPlugin\Api\CacheAuthorizeClientApiInterface' - '@Sylius\PayPalPlugin\Api\OrderDetailsApiInterface' - '@Sylius\PayPalPlugin\Provider\OrderProviderInterface'
Sylius\PayPalPlugin\Controller\ProcessPayPalOrderAction: alias: App\Controller\ProcessPayPalOrderAction
App\Controller\CompletePayPalOrderFromPaymentPageAction: class: App\Controller\CompletePayPalOrderFromPaymentPageAction public: true arguments: - '@Sylius\PayPalPlugin\Manager\PaymentStateManagerInterface' - '@router' - '@Sylius\PayPalPlugin\Provider\OrderProviderInterface' - '@syliusabstraction.statemachine' - '@sylius.manager.order' - '@sylius.orderprocessing.orderprocessor'
Sylius\PayPalPlugin\Controller\CompletePayPalOrderFromPaymentPageAction: alias: App\Controller\CompletePayPalOrderFromPaymentPageAction
Sylius\PayPalPlugin\Payum\Action\CaptureAction: class: App\Payum\Action\CaptureAction public: true arguments: - '@Sylius\PayPalPlugin\Api\CacheAuthorizeClientApiInterface' - '@Sylius\PayPalPlugin\Api\CreateOrderApiInterface' - '@Sylius\PayPalPlugin\Provider\UuidProviderInterface' tags: - { name: 'payum.action', factory: 'sylius.paypal', alias: 'payum.action.capture' }
or when using PayPal 2.x:
yaml services: App\Controller\ProcessPayPalOrderAction: class: App\Controller\ProcessPayPalOrderAction public: true arguments: - '@sylius.repository.customer' - '@sylius.factory.customer' - '@sylius.factory.address' - '@sylius.manager.order' - '@syliusabstraction.statemachine' - '@syliuspaypal.manager.paymentstate' - '@syliuspaypal.api.cacheauthorizeclient' - '@syliuspaypal.api.orderdetails' - '@syliuspaypal.provider.order'
syliuspaypal.controller.processpaypalorder: alias: App\Controller\ProcessPayPalOrderAction
App\Controller\CompletePayPalOrderFromPaymentPageAction: class: App\Controller\CompletePayPalOrderFromPaymentPageAction public: true arguments: - '@syliuspaypal.manager.paymentstate' - '@router' - '@syliuspaypal.provider.order' - '@syliusabstraction.statemachine' - '@sylius.manager.order' - '@sylius.orderprocessing.orderprocessor'
syliuspaypal.controller.completepaypalorderfrompaymentpage: alias: App\Controller\CompletePayPalOrderFromPaymentPageAction
syliuspaypal.payum.action.capture: class: App\Payum\Action\CaptureAction public: true arguments: - '@syliuspaypal.api.cacheauthorizeclient' - '@syliuspaypal.api.createorder' - '@syliuspaypal.provider.uuid' tags: - { name: 'payum.action', factory: 'sylius.paypal', alias: 'payum.action.capture' }
For more information
If you have any questions or comments about this advisory: Open an issue in Sylius issues Email us at security@sylius.com