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Missing AuthenticationWeakness · CWE-306

CVE-2025-40771

CRITICAL · 9.8 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 →
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 CP 1542SP-1 (6GK7542-6UX00-0XE0) (All versions < V2.4.24), SIMATIC CP 1542SP-1 IRC (6GK7542-6VX00-0XE0) (All versions < V2.4.24), SIMATIC CP 1543SP-1 (6GK7543-6WX00-0XE0) (All versions < V2.4.24), SIPLUS ET 200SP CP 1542SP-1 IRC TX RAIL (6AG2542-6VX00-4XE0) (All versions < V2.4.24), SIPLUS ET 200SP CP 1543SP-1 ISEC (6AG1543-6WX00-7XE0) (All versions < V2.4.24), SIPLUS ET 200SP CP 1543SP-1 ISEC TX RAIL (6AG2543-6WX00-4XE0) (All versions < V2.4.24). Affected devices do not properly authenticate configuration connections. This could allow an unauthenticated remote attacker to access the configuration data.

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 CP 1542SP-1 and CP 1543SP-1 communication processors contain an authentication bypass vulnerability in their configuration interface. Affected devices fail to properly authenticate configuration connections, allowing an unauthenticated remote attacker to access sensitive configuration data without any credentials.

MitigationUpgrade SIMATIC CP devices to firmware version V2.4.24 or later. Alternatively, implement network segmentation and firewall rules to restrict access to the configuration interface to only trusted networks/management stations.

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

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. Identify the device model
    Access the device web interface, check the device nameplate, or use network discovery tools to confirm the exact model is SIMATIC CP 1542SP-1 or CP 1543SP-1
    Affected if The device model is CP 1542SP-1 or CP 1543SP-1 and the firmware version is earlier than V2.4.24
  2. Determine the firmware version
    Log into the device configuration interface and navigate to the firmware or device information section, or use Siemens-specific management tools like TIA Portal or web-based device management to retrieve the installed firmware version
    Affected if The installed firmware version is earlier than V2.4.24
  3. Verify configuration interface exposure
    Check network configuration settings to determine if the device configuration interface (web server port or management ports) is accessible from untrusted or external network segments
    Affected if The configuration interface is reachable from untrusted networks without proper network segmentation
  4. Check for unauthorized configuration access
    Review device logs, access logs, or security monitoring systems for any configuration access attempts that occurred without proper authentication
    Affected if There are configuration access events in logs that lack associated authentication records or originate from unexpected sources

The environment is affected if a SIMATIC CP 1542SP-1 or CP 1543SP-1 device has firmware earlier than V2.4.24 and its configuration interface is accessible from untrusted networks.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade SIMATIC CP devices to firmware version V2.4.24 or later. Alternatively, implement network segmentation and firewall rules to restrict access to the configuration interface to only trusted networks/management stations.

Recommended fix High confidence

V2.4.24 or later for SIMATIC CP 1542SP-1, SIMATIC CP 1542SP-1 IRC, SIMATIC CP 1543SP-1, and SIPLUS ET 200SP CP 1542SP-1 IRC TX RAIL / CP 1543SP-1 ISEC variants

  1. 1. Identify all affected SIMATIC CP 1542SP-1, CP 1542SP-1 IRC, CP 1543SP-1, and SIPLUS ET 200SP CP devices in the inventory
  2. 2. Backup current configuration of each affected device before making changes
  3. 3. Obtain the firmware update V2.4.24 or later from Siemens (via cert-portal.siemens.com or official Siemens support channels)
  4. 4. Following Siemens documentation, upload and install firmware version V2.4.24 or newer on each affected device
  5. 5. After upgrade, verify that configuration connections now require proper authentication
  6. 6. Confirm the device firmware version has been updated successfully
Caveat Review Siemens release notes for V2.4.24 to check for any compatibility or configuration changes that may affect existing systems

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

Have this fixed Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,280
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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-2025-40771 in production — separate from our analysis above.

No notes yet

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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