CVE-2020-14002Network attack vector

First-connection targeting via host-key algorithm reordering

Published Jun 29, 2020 · Updated Aug 4, 2024

Information disclosure in PuTTY 0.68 through 0.73 allows man-in-the-middle attackers to identify likely first-time SSH connections. PuTTY's dynamic host-key policy moves a cached non-default key algorithm ahead in the client key-exchange list, exposing cached-key state on the wire. An attacker must intercept the initial exchange; the signal helps select connections lacking a cached key for host-key substitution but does not itself suppress PuTTY's warning.

CVSS severity5.9
Medium
EPSS probability3.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in PuTTY 0.68 through 0.73 allows man-in-the-middle attackers to identify likely first-time SSH connections. PuTTY's dynamic host-key policy moves a cached non-default key algorithm ahead in the client key-exchange list, exposing cached-key state on the wire. An attacker must intercept the initial exchange; the signal helps select connections lacking a cached key for host-key substitution but does not itself suppress PuTTY's warning.

The record

CVE
CVE-2020-14002
Published
Jun 29, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-203, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 29, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:P/I:N/A:N
4.7FZI Research Center for Information TechnologyCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-203Observable Discrepancy
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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