CNIL regulates multi-device cookie consent synchronization

The CNIL has established new regulations regarding multi-device cookie consent. According to a deliberation published in the Official Journal on January 18, 2026, websites and advertising networks may now apply a single consent choice across all devices used by a logged-in user.

Previously, users had to provide separate consent for every individual device, such as a mobile phone, computer, or Smart TV. This new framework is optional and strictly limited to authenticated environments; synchronization is only permitted if the user is logged into an account on each device. It cannot be applied to anonymous terminals based solely on shared IP addresses or Wi-Fi networks.

To ensure transparency, websites must notify users during the initial banner display that their choice will apply across all devices. Additionally, users must be notified when logging into a new terminal that their existing preferences will be applied. The regulation mandates that refusing consent must be as simple as accepting it. Furthermore, technical teams must implement pseudonymization, as transmitting account identifiers like email addresses to advertising providers or consent management platforms is now prohibited.