Comment by Insimwytim
7 hours ago
Most non-browser TLS clients (so basically everything else, with default settings), things like curl, Python, Node, Go, Java, git, package managers and every script and daemon you've got, do three things that matter here: they trust a CA bundle on disk, they don't check revocation by default, and they don't check CT. So the fact that eMudhra and Sectigo have revoked these intermediates doesn't help them at all. [1]
Couldn't this be enforced at the router? Intercept outbound TLS. If the client hello is to a new domain, hold it and start a new outbound connection and see if the server responds with a certificate on the CRL. If so, ban it. Otherwise let the original TLS connection proceed.
That would work with TLS 1.2, but not TLS 1.3. TLS 1.3 sends the certificate after the session key is derived and symmetric encryption is established.