Effective April 29, 2022, you will be able to stop allowing domain fronting behavior on your Azure Front Door, Azure Front Door (classic), and Azure CDN Standard from Microsoft (classic) resources in alignment with Microsoft’s commitment to secure our approach to domain fronting within Azure.
If you wish to block domain fronting for any existing or new (created after April 29, 2022) Azure Front Door, Azure Front Door (classic) and Azure CDN Standard from Microsoft (classic) resources, please create a support request and provide your subscription and Azure Front Door, Azure Front Door (classic), or Azure CDN Standard from Microsoft (classic) resource information. Upon enabling of blocking domain fronting behavior, Azure Front Door, Azure Front Door (classic), and Azure CDN Standard from Microsoft (classic) resources will block any HTTP request that exhibit this behavior.