CVE-2011-20001Network attack vector

Controller stop via malformed HTTP traffic

Published Oct 14, 2025 · Updated Oct 14, 2025

Improper input validation in Siemens SIMATIC S7-1200 CPU firmware before 2.0.3 allows remote attackers to stop the controller via HTTP. The embedded web server processes malformed HTTP traffic sent at high rate until a communications error drives the CPU into its defined stop/defect state. No authentication or user interaction is required, but the web server must be enabled and network-reachable; the resulting state stops the controlled process.

CVSS severity8.7
High
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Siemens SIMATIC S7-1200 CPU firmware before 2.0.3 allows remote attackers to stop the controller via HTTP. The embedded web server processes malformed HTTP traffic sent at high rate until a communications error drives the CPU into its defined stop/defect state. No authentication or user interaction is required, but the web server must be enabled and network-reachable; the resulting state stops the controlled process.

The record

CVE
CVE-2011-20001
Published
Oct 14, 2025
Updated
Oct 14, 2025
Vendor
Siemens
Product
SIMATIC S7-1200 CPU Family
Classifications
CWE-20, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 14, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 14, 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=0 <V2.0.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SIMATIC S7-1200 CPU Familyversion=0 <V2.0.3

Published CVSS scores

7.5Siemens AGCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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

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.

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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-20Improper Input Validation
T0814Denial of Service

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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