Google is a major player with the Chromium project and products based on it such as Google Chrome and Microsoft Edge have moved to implement the RFC 2818 and to no longer trust certificates that no longer fulfill this requirement.
For us, the following sentence is of great explosiveness:
Continue reading „DNS-Namen automatisch in den Subject Alternate Name (SAN) ausgestellter Zertifikate eintragen – mit dem TameMyCerts Policy Modul für Microsoft Active Directory Certificate Services (ADCS)“If a subjectAltName extension of type dNSName is present, that MUST be used as the identity. Otherwise, the (most specific) Common Name field in the Subject field of the certificate MUST be used. Although the use of the Common Name is existing practice, it is deprecated and Certification Authorities are encouraged to use the dNSName instead
https://tools.ietf.org/html/rfc2818
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