CVE-2021-36367

low
Published — · Modified —
CVSS v3
CVSS v2
VIR risk
2.5

Description

PuTTY through 0.75 proceeds with establishing an SSH session even if it has never sent a substantive authentication response. This makes 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).

Predictions

Exploit likelihood
20%
Patch ETA

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2021-36367

vendor Authored 2026-05-27

Vendor advisory: arch — https://security.archlinux.org/ASA-202107-37

OS impact

OSVersionStatusFixed in
arch archfixed0.76-1
debian debianbookwormfixed0.75-3
debian debianbullseyefixed0.74-1+deb11u1
debian debianforkyfixed0.75-3
debian debiansidfixed0.75-3
debian debiantrixiefixed0.75-3

References

Verify integrity in audit chain (admin only). AS-IS.