Affected versions of Sylius give attackers the ability to switch channels via the _channel_code GET parameter in production environments. This was meant to be enabled only when kernel.debug is set to true. However, if no sylius_channel.debug is set explicitly in the configuration, the default value which is kernel.debug will be not resolved and cast to boolean, enabling this debug feature even if that parameter is set to false. Patch has been provided for Sylius 1.3.x and newer – 1.3.16, 1.4.12, 1.5.9, 1.6.5. Versions older than 1.3 are not covered by our security support anymore.