CVE-2020-14145

A flaw was found in OpenSSH in versions 5.7 through 8.3, where an Observable Discrepancy occurs and leads to an information leak in the algorithm negotiation. This flaw allows a man-in-the-middle attacker to target initial connection attempts, where there is no host key for the server that has been cached by the client.

This is a flaw in OpenSSH, which allows a man in the middle attack to determine, if a client already has prior knowledge of the remote hosts fingerprint. An attacker could use this information to ignore clients, which will show an error message during an man in the middle attack, while new clients can be intercepted without alerting them of the man in the middle attack.

This essentially means that this flaw can help attacker's identify targets an MITM attack. However such a attack would still require the attacker to either have control over DNS or control over the network traffic.

If the network is untrusted, Red Hat suggests the use ssh certificates for even more confidence and less human factor involved or gssapi key exchange, where kerberos is used to verify identity of the server.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Always connect to SSH servers with verified host keys to avoid any possibilities of man-in-the-middle attack.