Sensitive Information Exposure in Sylius

Impact

Any other user can view the data if the browser tab remains open after logging out. Once someone logs out and leaves the browser open, the potential attacker may use the back button to see the content exposed on given screens. No action may be performed though, and any website refresh will block further reads. It may, however, lead to a data leak, like for example customer details, payment gateway configuration, etc.- but only if these were pages checked by the administrator.

This vulnerability requires full access to the computer to take advantage of it.

Patches

The issue is fixed in versions: 1.9.10, 1.10.11, 1.11.2 and above.

Workarounds

The application must strictly redirect to the login page even when the browser back button is pressed. Another possibility is to set more strict cache policies for restricted content (like no-store). It can be achieved with the following class:

<?php

declare(strict_types=1);

namespace App\EventListener;

use App\SectionResolver\ShopCustomerAccountSubSection;
use Sylius\Bundle\AdminBundle\SectionResolver\AdminSection;
use Sylius\Bundle\CoreBundle\SectionResolver\SectionProviderInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpKernel\Event\ResponseEvent;
use Symfony\Component\HttpKernel\KernelEvents;

final class CacheControlSubscriber implements EventSubscriberInterface
{
    /** @var SectionProviderInterface */
    private $sectionProvider;

    public function __construct(SectionProviderInterface $sectionProvider)
    {
        $this->sectionProvider = $sectionProvider;
    }

    public static function getSubscribedEvents(): array
    {
        return [
            KernelEvents::RESPONSE => 'setCacheControlDirectives',
        ];
    }

    public function setCacheControlDirectives(ResponseEvent $event): void
    {
        if (
            !$this->sectionProvider->getSection() instanceof AdminSection &&
            !$this->sectionProvider->getSection() instanceof ShopCustomerAccountSubSection
        ) {
            return;
        }

        $response = $event->getResponse();

        $response->headers->addCacheControlDirective('no-cache', true);
        $response->headers->addCacheControlDirective('max-age', '0');
        $response->headers->addCacheControlDirective('must-revalidate', true);
        $response->headers->addCacheControlDirective('no-store', true);
    }
}

After that register service in the container:

services:
    App\EventListener\CacheControlSubscriber:
        arguments: ['@sylius.section_resolver.uri_based_section_resolver']
        tags:
            - { name: kernel.event_subscriber, event: kernel.response }

The code above requires changes in ShopUriBasedSectionResolver in order to work. To backport mentioned logic, you need to replace the class with: