As a first step I tried to make sure this actually is a change in openssh. Because my reading of the issues referred above has shown that not all of the verification is done inside ssh but partially in glibc.
So I upgraded on the bionic test system step by step. The upgrade dependency list for openssh-client is "libc-bin libc6 libgssapi-krb5-2 libkrb5-3 libkrb5support0 locales" I found that the bug is reproducible with openssh-client 1:7.6p1-4ubuntu0.3 running against the newer glibc. I can switch in/out the reported bug be switching on a Bionic system between glibc 2.27-3ubuntu1.2 - Bionic - Good 2.31-0ubuntu9.1 - Focal - Bad ** Also affects: glibc (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1898590 Title: Verify DNS fingerprints not working To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1898590/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs