I agree. The article even says that these odd formats are used to bypass filters but cannot pinpoint why BSD 4.2 added support for them in 1983.

It hints that certificate validation fails in some cases, but that seems even more niche. What applications are using certs with IP-in-CN anyway in 2021? Shouldn't any IPs be in the "typed" SAN extension?

Commit is here: https://github.com/curl/curl/commit/56a037cc0ad1b2a770d0c08d...