As part of Microsoft’s commitment to secure our approach to domain fronting within Azure, Azure Front Door (including classic) and Azure CDN Standard from Microsoft (classic) have blocked domain fronting for newly created resources since November, 2022.
Based on customer feedback and security considerations, Azure Front Door and Azure CDN Standard from Microsoft (classic) have revised the domain fronting blocking restrictions effective from September 25, 2023. Instead of blocking a request when the TLS SNI extension and the host header do not match, Azure Front Door will allow the mismatch if both values are added as domains in the same Azure subscription.
For more information, please refer to the Azure Front Door – Frequently asked questions document.
