Debian LTS DLA-3794-1 Critical: Putty SSH Threat Remediation

CVE-2019-17069

PuTTY allowed remote SSH-1 servers to cause a denial
of service by accessing freed memory locations via an
SSH1_MSG_DISCONNECT message.

CVE-2020-14002

PuTTY had an Observable Discrepancy leading to an
information leak in the algorithm negotiation.
This allowed man-in-the-middle attackers to target
initial connection attempts (where no host key for the
server has been cached by the client).

CVE-2021-36367

PuTTY proceeded with establishing an SSH session even
if it has never sent a substantive authentication response.
This made it easier for an attacker-controlled SSH server
to present a later spoofed authentication prompt (that the
attacker can use to capture credential data, and use that
data for purposes that are undesired by the client user).

CVE-2023-48795

PuTTY was vulnerable to Terrapin attack. The SSH transport
protocol with certain OpenSSH extensions, allowed remote attackers
to bypass integrity checks such that some packets are omitted (from