curl: An improper certificate validation vulnerability exists in curl <v8.1.0 inthe way it supports matching of wildcard pa...

An improper certificate validation vulnerability exists in curl <v8.1.0 inthe way it supports matching of wildcard patterns when listed as "SubjectAlternative Name" in TLS server certificates. curl can be built to use itsown name matching function for TLS rather than one provided by a TLSlibrary. This private wildcard matching function would match IDN(International Domain Name) hosts incorrectly and could as a result acceptpatterns that otherwise should mismatch. IDN hostnames are converted topuny code before used for certificate checks. Puny coded names always startwith `xn--` and should not be allowed to pattern match, but the wildcardcheck in curl could still check for `x*`, which would match even though theIDN name most likely contained nothing even resembling an `x`.

Where it's fixed