CVE-2021-36367

What it is

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).

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. High risk of data exposure, data tampering.

Exploit odds

1.1% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2021-07-09 00:00 UTC ReservedThe CVE id was reserved by its CNA
2. 2021-07-09 21:15 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-06-17 03:58 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.1% in the next 30 days (EPSS).
• Severity: 8.1 HIGH (CVSS).
• Fix: none linked yet, which raises it.

Details

Published

2021-07-09 21:15 UTC

Last modified

2026-06-17 03:58 UTC

Exploit probability

1.1% · EPSS, next 30 days

Weakness

CWE-345

Record status

Modified

Affected

• Putty ≤ 0.75

Attack profile CVSS 3.1 · 8.1

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-36367.md and follow it. Check whether this project is affected by CVE-2021-36367. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

Copy as ticket · More options · Status badge