View at Official ubuntu advisory, NVD, CVE.org · CVE detail
Freshness: upstream tracker timestamp is available; use API updated time as primary recency signal.
CVE-2016-20012 negligible priority: Ubuntu including 2 source packages (openssh, openssh-ssh1), 16 status rows across 8 suites (bionic, focal, hirsute, impish, jammy, trusty, upstream, xenial): ignored 14, DNE 2.
OpenSSH through 8.7 allows remote attackers, who have a suspicion that a certain combination of username and public key is known to an SSH server, to test whether this suspicion is correct. This occurs because a challenge is sent only when that combination could be valid for a login session. NOTE: the vendor does not recognize user enumeration as a vulnerability for this product