transport.py in the SSH server implementation of Paramiko before 1.17.6, 1.18.x before 1.18.5, 2.0.x before 2.0.8, 2.1.x before 2.1.5, 2.2.x before 2.2.3, 2.3.x before 2.3.2, and 2.4.x before 2.4.1 does not properly check whether authentication is completed before processing other requests, as demonstrated by channel-open. A customized SSH client can simply skip the authentication step.
access.redhat.com/errata/RHSA-2018:0591
access.redhat.com/errata/RHSA-2018:0646
access.redhat.com/errata/RHSA-2018:1124
access.redhat.com/errata/RHSA-2018:1125
access.redhat.com/errata/RHSA-2018:1213
access.redhat.com/errata/RHSA-2018:1274
access.redhat.com/errata/RHSA-2018:1328
access.redhat.com/errata/RHSA-2018:1525
access.redhat.com/errata/RHSA-2018:1972
github.com/advisories/GHSA-232r-66cg-79px
github.com/paramiko/paramiko
github.com/paramiko/paramiko/blob/e861c7697622774071ce73b46ffe8817eacdedfa/sites/www/changelog.rst?plain=1#L759-L763
github.com/paramiko/paramiko/commit/e9dfd854bdaf8af15d7834f7502a0451d217bb8c
github.com/paramiko/paramiko/commit/fa29bd8446c8eab237f5187d28787727b4610516
github.com/paramiko/paramiko/issues/1175
lists.debian.org/debian-lts-announce/2018/10/msg00018.html
lists.debian.org/debian-lts-announce/2021/12/msg00025.html
nvd.nist.gov/vuln/detail/CVE-2018-7750
usn.ubuntu.com/3603-1
usn.ubuntu.com/3603-2
web.archive.org/web/20190831123128/www.securityfocus.com/bid/103713
www.exploit-db.com/exploits/45712