Improper Input ValidationWeakness · CWE-20

CVE-2011-20001

HIGH · 7.5 CVSS v3.1 Published 2025-10-14

Mitigation only

No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.

See remediation →

84/100

Remediation priority · High

Remotely reachable No privileges Zero-click

Official description

NVD · unedited

A vulnerability has been identified in SIMATIC S7-1200 CPU V1 family (incl. SIPLUS variants) (All versions < V2.0.3), SIMATIC S7-1200 CPU V2 family (incl. SIPLUS variants) (All versions < V2.0.3). The web server interface of affected devices improperly processes incoming malformed HTTP traffic at high rate. This could allow an unauthenticated remote attacker to force the device entering the stop/defect state, thus creating a denial of service condition.

Technical summary

dbcve analysis · high confidence

The web server interface in Siemens SIMATIC S7-1200 CPU V1 and V2 family PLCs (versions below V2.0.3) improperly handles malformed HTTP traffic received at high rates. This processing flaw causes the device to crash into a stop/defect state, resulting in a denial of service. The attack is exploitable remotely by unauthenticated attackers via the web server port.

MitigationUpdate firmware to V2.0.3 or later per Siemens advisory. Until patched, isolate the web server interface behind a firewall or VPN, and implement rate limiting at the network perimeter to reduce malformed traffic exposure.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown

From the vector

Attack vector: Network
Complexity: Low
Privileges: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Confirm SIMATIC S7-1200 model

Access the PLC via TIA Portal or STEP 7, or physically check the device nameplate, to confirm the device is a SIMATIC S7-1200 CPU V1 or V2 family PLC

Affected if Device is not a SIMATIC S7-1200 CPU V1 or V2 variant
Identify firmware version

In TIA Portal or STEP 7, go to the PLC properties and read the firmware version field. Alternatively, access the built-in web server and check the version information displayed on the homepage

Affected if Firmware version is below V2.0.3 (for example, V2.0.2, V2.0.1, V1.x)
Verify web server is enabled

In TIA Portal or STEP 7, open the PLC properties and check if the Web server feature is enabled under the Web server settings. You can also probe ports 80 or 443 on the device IP address

Affected if Web server interface is enabled and accessible on the network

The device is affected if it is a SIMATIC S7-1200 CPU V1 or V2 with firmware below V2.0.3 and the web server interface is enabled, exposing it to remote unauthenticated DoS via malformed HTTP traffic.

Generated from the published advisory. Verify against your own configuration.

Remediation

dbcve · scoped

Mitigation available No clean upgrade yet — mitigate in the meantime

Mitigation

Update firmware to V2.0.3 or later per Siemens advisory. Until patched, isolate the web server interface behind a firewall or VPN, and implement rate limiting at the network perimeter to reduce malformed traffic exposure.

Recommended fix Moderate confidence

SIMATIC S7-1200 CPU V1/V2 family firmware V2.0.3 or later

Identify the current firmware version of the SIMATIC S7-1200 CPU via the web server interface or TIA Portal
Download the V2.0.3 firmware update or later from Siemens Industry Online Support (support.industry.siemens.com)
Back up the current CPU project/program before performing the firmware update
Use TIA Portal or appropriate firmware update tool to upload the V2.0.3 (or later) firmware to the CPU
After the update completes, verify the device is running the new firmware version via the web server
Confirm the web server is operational and the device is in RUN mode

Caveat Review Siemens release notes for V2.0.3 for any compatibility or functional changes before upgrading; firmware updates may require project adjustments

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory

Consultation4.0 h
Implementation3.0 h
Testing6.0 h
Review / QA3.0 h

16.0 hours of engineering $2,780

Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,448.

Scan for this in your stack

Free · runs locally

dbcve dependency scanner

Check whether your project pulls in CVE-2011-20001 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References

Primary sources

cert-portal.siemens.com
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2011-20001 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2011-20001?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

A fix existsA vendor remedy is published

Severity 7.5 High

Exploit likelihood EPSS, next 30 days 0.5%

Remediation

A high-priority fix

Have this fixed 16 hrs · Moderate

Typical engagement from $2,780

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2011-20001 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

Check your environment

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

CVSS breakdown

Am I affected?

Remediation

References