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.

Affected: Ubuntu:14.04:LTS: paramiko, Ubuntu:16.04:LTS: paramiko

Matthijs Kooijman discovered that Paramiko's SSH server implementation did not properly require authentication before processing requests. An unauthenticated remote attacker could possibly use this to execute arbitrary code.