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Simatic Cn 4100 FirmwareOperating system · Siemens

CVE-2025-40938

CRITICAL · 9.8 CVSS v3.1 Published 2025-12-09
Fix available
A fix is available. Upgrade to 4.0.1 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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.

NVD · unedited
A vulnerability has been identified in SIMATIC CN 4100 (All versions < V4.0.1). The affected device stores sensitive information in the firmware. This could allow an attacker to access and misuse this information, potentially impacting the device’s confidentiality, integrity, and availability.

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.

dbcve analysis · moderate confidence

The SIMATIC CN 4100 device stores sensitive information (such as credentials, keys, or configuration data) directly in the firmware image. An attacker who obtains the firmware (through extraction, download, or supply chain access) can extract this sensitive data, potentially gaining administrative access, cryptographic keys, or network credentials that could be used to compromise the device or the broader industrial network.

MitigationUpdate SIMATIC CN 4100 devices to firmware version V4.0.1 or later, which should relocate sensitive data out of firmware storage. If updating is not immediately possible, implement network segmentation and access controls to limit exposure if firmware extraction occurs.

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

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Simatic Cn 4100 FirmwareOperating system
Affected:< 4.0.1

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.

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

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

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.

dbcve checks

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

  1. Confirm device model
    Identify if the target device is a Siemens SIMATIC CN 4100. Check the device label, packaging, or network inventory for the model designation.
    Affected if Device is not a SIMATIC CN 4100, then this specific CVE does not apply
  2. Retrieve firmware version via web interface
    Log into the device web interface (if accessible) and navigate to the System Information or Device Status page to view the installed firmware version.
    Affected if Firmware version shown is below 4.0.1 (for example, 3.x.x or 4.0.0)
  3. Retrieve firmware version via CLI
    Access the device command line interface (via SSH or console) and run the appropriate command to display firmware version, such as 'show version' or 'system info'.
    Affected if Firmware version shown is below 4.0.1
  4. Extract firmware version from firmware file
    If you have a firmware image file, use binwalk, strings, or a firmware extraction tool to extract the version string from the firmware binary.
    Affected if Extracted version string indicates a version below 4.0.1

You are affected if the device is a Siemens SIMATIC CN 4100 running firmware version below V4.0.1.

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

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Upgrade available Upgrade to 4.0.1 or later
Fixed in 4.0.1
Interim mitigation

Update SIMATIC CN 4100 devices to firmware version V4.0.1 or later, which should relocate sensitive data out of firmware storage. If updating is not immediately possible, implement network segmentation and access controls to limit exposure if firmware extraction occurs.

Recommended fix High confidence

V4.0.1

  1. Download the V4.0.1 firmware update for SIMATIC CN 4100 from the official Siemens support portal (cert-portal.siemens.com or siemens.com)
  2. Review the firmware upgrade instructions and release notes before proceeding
  3. Create a backup of the current device configuration if supported
  4. Access the device management interface and navigate to the firmware update section
  5. Upload and apply the V4.0.1 firmware to the affected device
  6. Allow the device to complete the firmware update process and reboot
  7. After upgrade, verify the device is running V4.0.1 or later
  8. Change any default credentials and implement strong, unique passwords for all accounts

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

Fix this in Simatic Cn 4100 Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA8.0 h
44.0 hours of engineering $7,720
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $12,352.

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

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-40938 in production — separate from our analysis above.

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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