Terrapin attacks can downgrade security of OpenSSH connectionsAcademic researchers developed a new attack called Terrapin that manipulates sequence numbers during the handshake process to breaks the SSH channel integrity when certain widely-used encryption modes are used. [...]
Source: Terrapin attacks can downgrade security of OpenSSH connections (https://www.bleepingcomputer.com/news/security/terrapin-attacks-can-downgrade-security-of-openssh-connections/)