A vulnerability in the SSH protocol can be exploited by a well-placed adversary to weaken the security of people’s connections, if conditions are right.
In a successful man-in-the-middle attack, the adversary may be able to force SSH clients to use weaker authentication methods and disable some defense mechanisms. It is hard right now to pin down the true realistic impact of the flaw because it all depends on individual client-server configurations, implementations of the protocol, and other variables. SSH is mainly used to connect into remote systems to use or administer them via a command-line interface.
