CVE-2024-0723Public exploitNetwork attack vector

Remote service interruption via oversized SSH handshakes

Published Jan 19, 2024 · Updated May 30, 2025

Denial of service in freeSSHd 1.0.9 on Windows allows remote attackers to interrupt the SSH service via malformed handshake data. The public proof of concept opens 19 TCP connections and sends each an oversized SSH-1.99 handshake payload containing more than 21 KB of crafted data. No authentication or user interaction is required; the SSH service becomes unresponsive, while the precise resource-handling locus remains undisclosed.

CVSS severity7.5
High
EPSS probability3.65%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in freeSSHd 1.0.9 on Windows allows remote attackers to interrupt the SSH service via malformed handshake data. The public proof of concept opens 19 TCP connections and sends each an oversized SSH-1.99 handshake payload containing more than 21 KB of crafted data. No authentication or user interaction is required; the SSH service becomes unresponsive, while the precise resource-handling locus remains undisclosed.

The record

CVE
CVE-2024-0723
Published
Jan 19, 2024
Updated
May 30, 2025
Vendor
Kresimir Petric
Product
freeSSHd
Classifications
CWE-404, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 19, 2024CVE publishedPublication date reported by the CVE source.
  2. May 30, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Kresimir Petric · freeSSHdversion=1.0.9

Published CVSS scores

5.0VulDBAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.3VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
5.3VulDBCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-404Improper Resource Shutdown or Release
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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