New Terrapin Flaw Could Let Attackers Downgrade SSH Protocol Security

Security researchers disclosed CVE-2023-48795 (“Terrapin”), a prefix-truncation attack against SSH extension negotiation that allows an active MITM to truncate messages and downgrade connection security (potentially weakening client authentication and disabling countermeasures); multiple SSH implementations are affected, patches have been released, and Shadowserver estimates ~11 million internet-exposed SSH servers remain vulnerable.