How does Cross Domain Consent Sharing work? – Usercentrics Support - EN

Activation procedure (V2)

Cross Domain Consent Sharing (CDCS) is available in the following plans: Business, Enterprise, Advanced as well as Premium Add-on.
You can enable this feature at the Admin Interface under the Configuration section, on the CMP Settings tab, in the CMP Settings section.

How does the feature work?

As soon as CDCS is activated, our CMP injects an additional iFrame into the website and stores the consent information not only in the websites local storage but also in the iFrame's local storage. While the user switches to another (sub-)domain, the iFrames local storage is checked and if consent information is found, the consent information from the iFrame is stored into the local storage of the new (sub-)domain.

For Cross Domain Consent Sharing to work, implement the same Usercentrics CMP script using one Settings-ID on all domains that should share consents.

Improved consent sharing between subdomains

Modern browsers are causing that website visitors might still see the CMP again when switching to another subdomain as they block the shared iframe provided by Usercentrics (s. Browser related restrictions). The following linked section in the documentation describes the needed steps to prevent this from happening: Improved consent sharing between subdomains.

Please note that there are still existing Safari browser restrictions that remain with this improved consent sharing.

Restrictions

Usercentrics related restrictions

In order to make this feature work, the same Setting-ID has to be implemented in all (sub-)domains the consent information should be shared across. This is due to technical and legal reasons.

Browser related restrictions

CDCS does not work without sharing 3rd-Party local storage information across different browser tabs or if the user enabled special privacy settings within the Browser settings.

Safari and Any: CDCS does not work with Safari, since the browser does not share 3rd-Party local storage across different browser tabs. Due to this restriction, the feature can not share the iFrame's local storage across different tabs.
Firefox Browser: If the option “Delete Cookies” is enabled, the feature does not work, since Firefox clears the local storage for every new tab automatically, which prevents saving consents.
iOS browsers and iOS devices: Apple forces all browsers to use their built-in webkit, so CDCS does not work with them.

There is no workaround to circumvent these restrictions since it is a functionality of the browser itself or based on custom privacy settings of a single user to protect his/her personal data.

Different root domains restriction

From Chrome version 115 and going forward, CDCS does not work between different root domains (ex. a.com → b.com) because of restrictions that Google have imposed on third-party storage possibilities. This means, that our current implementation of CDCS now effectively only works between root domains and their subdomains (ex. sub.a.com → a.com → othersub.a.com).

Read more about the updates that Google have made to Chrome here: Storage Partitioning | Privacy Sandbox | Google for Developers

Cross Domain Consent Sharing is also available for TCF 2.2.

Summary

After reading this article, you should be able to understand the technical as well as the legal concepts of Cross Domain Consent Sharing.