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Simatic Cn 4100 FirmwareOperating system · Siemens

CVE-2026-22925

HIGH · 7.5 CVSS v3.1 Published 2026-05-12
Fix available
A fix is available. Upgrade to 5.0 or later.
See remediation →
84/100
Remediation priority · High
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 < V5.0). The affected application is susceptible to resource exhaustion when subjected to high volume of TCP SYN packets This could allow an attacker to render the service unavailable and cause denial-of-service conditions by overwhelming system resources.

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 · high confidence

The SIMATIC CN 4100 application (versions prior to V5.0) is vulnerable to resource exhaustion when subjected to high volumes of TCP SYN packets, enabling attackers to overwhelm system resources and cause denial-of-service conditions through a SYN flood attack.

MitigationUpgrade to V5.0 or later; implement SYN flood protection (SYN cookies, increased SYN queue size) at network perimeter or deploy rate-limiting/IPS filtering to block excessive SYN packets.

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:< 5.0

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
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? 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. Identify the device model
    Log into the device web interface or check the device nameplate documentation to confirm the hardware is a Siemens SIMATIC CN 4100.
    Affected if The device is confirmed to be a SIMATIC CN 4100 unit.
  2. Determine the firmware version
    Access the device web interface or use the device management software to view the firmware version information. This is typically found under System Information or Device Status in the admin panel.
    Affected if The displayed firmware version is below V5.0 (for example, V4.x or earlier).
  3. Verify the version number format
    Confirm the exact version string displayed matches the Siemens versioning convention (such as V4.9, V4.8, V4.7, etc.). Ensure you are reading the firmware version and not another software component version.
    Affected if The firmware version string indicates a version less than 5.0.

If the device is a SIMATIC CN 4100 running firmware version V5.0 or later, it is not affected; any version prior to V5.0 is vulnerable to this SYN flood resource exhaustion.

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 5.0 or later
Fixed in 5.0
Interim mitigation

Upgrade to V5.0 or later; implement SYN flood protection (SYN cookies, increased SYN queue size) at network perimeter or deploy rate-limiting/IPS filtering to block excessive SYN packets.

Recommended fix High confidence

Firmware V5.0 or later

  1. 1. Identify the current firmware version of the SIMATIC CN 4100 device via the device web interface or TIA Administration console
  2. 2. Navigate to the Siemens Industry Online Support portal (support.industry.siemens.com) and locate the SIMATIC CN 4100 product page
  3. 3. Download the firmware version V5.0 or later from the Siemens support site
  4. 4. Review the firmware upgrade instructions in the device manual or Siemens firmware release notes
  5. 5. Upload the new firmware file to the device using the TIA Administration console or device web interface, following the documented upgrade procedure
  6. 6. After the firmware update completes, verify the device is operational and confirm the new firmware version is V5.0 or higher
  7. 7. Test normal device functionality to ensure the update was successful
Caveat Review Siemens release notes for any configuration or compatibility changes between your current version and V5.0 before upgrading

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

Fix this in Simatic Cn 4100 Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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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-2026-22925 in production — separate from our analysis above.

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What this is

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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