OpenSSH through 7.7 is prone to a user enumeration vulnerability due to not delaying bailout for an invalid authenticating user until after the packet containing the request has been fully parsed, related to auth2-gss.c, auth2-hostbased.c, and auth2-pubkey.c.
https://www.oracle.com/security-alerts/cpujan2020.html
https://www.exploit-db.com/exploits/45939/
https://www.exploit-db.com/exploits/45233/
https://www.exploit-db.com/exploits/45210/
https://www.debian.org/security/2018/dsa-4280
https://usn.ubuntu.com/3809-1/
https://security.netapp.com/advisory/ntap-20181101-0001/
https://security.gentoo.org/glsa/201810-03
https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2018-0011
https://lists.debian.org/debian-lts-announce/2018/08/msg00022.html
https://github.com/openbsd/src/commit/779974d35b4859c07bc3cb8a12c74b43b0a7d1e0
https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
https://bugs.debian.org/906236
https://access.redhat.com/errata/RHSA-2019:2143
https://access.redhat.com/errata/RHSA-2019:0711
http://www.securitytracker.com/id/1041487