CVE-2024-43647Network attack vector

Unauthenticated persistent service interruption via malformed TCP packet

Published Sep 10, 2024 · Updated Sep 10, 2024

Denial of service in all versions of Siemens SIMATIC S7-200 SMART CPUs allows remote attackers to hang devices with a malformed TCP packet. The TCP packet-processing path fails to reject an incorrectly structured packet, leaving the controller unresponsive without automatic recovery. No authentication is required, and the consequence is a persistent service interruption rather than data disclosure or modification.

CVSS severity8.7
High
EPSS probability0.56%
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 all versions of Siemens SIMATIC S7-200 SMART CPUs allows remote attackers to hang devices with a malformed TCP packet. The TCP packet-processing path fails to reject an incorrectly structured packet, leaving the controller unresponsive without automatic recovery. No authentication is required, and the consequence is a persistent service interruption rather than data disclosure or modification.

The record

CVE
CVE-2024-43647
Published
Sep 10, 2024
Updated
Sep 10, 2024
Vendor
Siemens
Product
SIMATIC S7-200 SMART CPU ST20
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 10, 2024CVE publishedPublication date reported by the CVE source.
  2. Sep 10, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0 <*

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SIMATIC S7-200 SMART CPU ST20version=0 <*
Siemens · SIMATIC S7-200 SMART CPU SR40version=0 <*
Siemens · SIMATIC S7-200 SMART CPU SR20version=0 <*
Siemens · SIMATIC S7-200 SMART CPU ST40version=0 <*
Siemens · SIMATIC S7-200 SMART CPU SR60version=0 <*
Siemens · SIMATIC S7-200 SMART CPU CR40version=0 <*
Siemens · SIMATIC S7-200 SMART CPU ST60version=0 <*
Siemens · SIMATIC S7-200 SMART CPU ST30version=0 <*
Siemens · SIMATIC S7-200 SMART CPU CR60version=0 <*
Siemens · SIMATIC S7-200 SMART CPU SR30version=0 <*

Published CVSS scores

8.7Siemens AGCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5Siemens AGCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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-400Uncontrolled Resource Consumption
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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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