The NSA said wildcard certificates are bad. Everyone uses them anyway.
In October 2021 the NSA published an advisory titled “Avoid Dangers of Wildcard TLS Certificates.” It reiterated what security consultants had been saying for years: don’t use wildcard certificates. Single-name certificates per host are safer. Five years later, we counted the certificates that are actually used. One in three domains has a wildcard on it. For.bank domains, where you need a security review just to register, it’s four in five. Operators aren’t careless.