Impact

URL to the payment page done after checkout was created with autoincremented payment id (/pay-with-paypal/{id}) and therefore it was easy to access for anyone, not even the order's customer. The problem was, the Credit card form has prefilled "credit card holder" field with the Customer's first and last name.
Additionally, the mentioned form did not require a 3D Secure authentication, as well as did not checked the result of the 3D Secure authentication.

Patches

The problem has been patched in Sylius/PayPalPlugin 1.2.4 and 1.3.1

Workarounds

One can override a sylius_paypal_plugin_pay_with_paypal_form route and change its URL parameters to (for example) {orderToken}/{paymentId}, then override the Sylius\PayPalPlugin\Controller\PayWithPayPalFormAction service, to operate on the payment taken from the repository by these 2 values. It would also require usage of custom repository method.
Additionally, one could override the @SyliusPayPalPlugin/payWithPaypal.html.twig template, to add contingencies: ['SCA_ALWAYS'] line in hostedFields.submit(...) function call (line 421). It would then have to be handled in the function callback.

For more information

If you have any questions or comments about this advisory:

• Open an issue in Sylius/PayPalPlugin issues
• Email us at security at sylius dot com