More information about this security flaw is available in the following bug: https://bugzilla.redhat.com/show_bug.cgi?id=2369388 Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
ssh_kdf() is a function from the libssh code base. libssh2 is an entirely different code base.