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Simatic S7 1200 FirmwareOperating system · Siemens

CVE-2019-13945

MEDIUM · 6.8 CVSS v3.1 Published 2019-12-12
Fix available
A fix is available. Upgrade to after 2.5.0 or later.
See remediation →
73/100
Remediation priority · Elevated
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 S7-1200 CPU family (incl. SIPLUS variants) (All versions), SIMATIC S7-1200 CPU family < V4.x (incl. SIPLUS variants) (All versions), SIMATIC S7-1200 CPU family V4.x (incl. SIPLUS variants) (All versions with Function State (FS) < 11), SIMATIC S7-200 SMART CPU CR20s (6ES7 288-1CR20-0AA1) (All versions <= V2.3.0 and Function State (FS) <= 3), SIMATIC S7-200 SMART CPU CR30s (6ES7 288-1CR30-0AA1) (All versions <= V2.3.0 and Function State (FS) <= 3), SIMATIC S7-200 SMART CPU CR40 (6ES7 288-1CR40-0AA0) (All versions <= V2.2.2 and Function State (FS) <= 8), SIMATIC S7-200 SMART CPU CR40s (6ES7 288-1CR40-0AA1) (All versions <= V2.3.0 and Function State (FS) <= 3), SIMATIC S7-200 SMART CPU CR60 (6ES7 288-1CR60-0AA0) (All versions <= V2.2.2 and Function State (FS) <= 10), SIMATIC S7-200 SMART CPU CR60s (6ES7 288-1CR60-0AA1) (All versions <= V2.3.0 and Function State (FS) <= 3), SIMATIC S7-200 SMART CPU SR20 (6ES7 288-1SR20-0AA0) (All versions <= V2.5.0 and Function State (FS) <= 11), SIMATIC S7-200 SMART CPU SR30 (6ES7 288-1SR30-0AA0) (All versions <= V2.5.0 and Function State (FS) <= 10), SIMATIC S7-200 SMART CPU SR40 (6ES7 288-1SR40-0AA0) (All versions <= V2.5.0 and Function State (FS) <= 10), SIMATIC S7-200 SMART CPU SR60 (6ES7 288-1SR60-0AA0) (All versions <= V2.5.0 and Function State (FS) <= 12), SIMATIC S7-200 SMART CPU ST20 (6ES7 288-1ST20-0AA0) (All versions <= V2.5.0 and Function State (FS) <= 9), SIMATIC S7-200 SMART CPU ST30 (6ES7 288-1ST30-0AA0) (All versions <= V2.5.0 and Function State (FS) <= 9), SIMATIC S7-200 SMART CPU ST40 (6ES7 288-1ST40-0AA0) (All versions <= V2.5.0 and Function State (FS) <= 8), SIMATIC S7-200 SMART CPU ST60 (6ES7 288-1ST60-0AA0) (All versions <= V2.5.0 and Function State (FS) <= 8), SIMATIC S7-200 SMART CPU family (All versions). There is an access mode used during manufacturing of the affected devices that allows additional diagnostic functionality. The security vulnerability could be exploited by an attacker with physical access to the UART interface during boot process.

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

A manufacturing backdoor/diagnostic access mode exists in the UART interface of SIMATIC S7-1200 and S7-200 SMART CPU families that can be exploited by an attacker with physical access to the UART interface during the boot process, allowing unauthorized diagnostic functionality.

MitigationApply vendor firmware updates when available and implement physical security controls to restrict access to device UART interfaces; coordinate with Siemens for patch availability.

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 S7 1200 FirmwareOperating system
Affected:all versions
S7 200 Smart FirmwareOperating system
Affected:all versions
Simatic S7 200 Smart Cpu St20 FirmwareOperating system
Affected:<= 2.5.0
Simatic S7 200 Smart Cpu St30 FirmwareOperating system
Affected:<= 2.5.0
Simatic S7 200 Smart Cpu St40 FirmwareOperating system
Affected:<= 2.5.0
Simatic S7 200 Smart Cpu St60 FirmwareOperating system
Affected:<= 2.5.0
Simatic S7 200 Smart Cpu Sr20 FirmwareOperating system
Affected:<= 2.5.0
Simatic S7 200 Smart Cpu Sr30 FirmwareOperating system
Affected:<= 2.5.0

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
Physical
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:P/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 PLC model and firmware version
    Locate the Siemens PLC (S7-1200 or S7-200 Smart variant ST20/ST30/ST40/ST60/SR20/SR30) and retrieve its firmware version from the device labeling, TIA Portal project, or via the device web interface if available
    Affected if The device is a SIMATIC S7-1200 (any firmware) or a S7-200 Smart CPU (ST20/ST30/ST40/ST60/SR20/SR30) with firmware version 2.5.0 or lower
  2. Assess physical location of the PLC
    Inspect the physical environment where the PLC is installed. Determine whether the device cabinet or enclosure is locked and whether the UART debugging port (typically a 9-pin D-sub or similar connector) is exposed or accessible without specialized tools
    Affected if The PLC is installed in an unsecured or publicly accessible location where an attacker could gain physical access to the UART interface
  3. Verify UART port protection
    Examine the PLC chassis for any external indicators of UART port protection such as port covers, removed headers, or tamper-evident seals on the debug/serial interface
    Affected if The UART/debugging port is physically exposed or unprotected, allowing connection without removing covers or tools
  4. Confirm boot process accessibility
    Determine whether the PLC can be powered cycled by an attacker without detection. Check if the device is in a monitored area and whether power cycles would be logged or noticed
    Affected if An attacker could physically power cycle the device and access the UART interface during the boot sequence without being detected

A user is affected if they have a SIMATIC S7-1200 (any version) or S7-200 Smart CPU (firmware <=2.5.0) deployed in a location where physical access to the UART interface is possible, enabling the diagnostic backdoor to be exploited.

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.

From vendor data
Upgrade available Upgrade to a release after 2.5.0
Interim mitigation

Apply vendor firmware updates when available and implement physical security controls to restrict access to device UART interfaces; coordinate with Siemens for patch availability.

Fix this in Simatic S7 1200 Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
36.0 hours of engineering $6,400
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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-2019-13945 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
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  • No spam, self-promotion, credentials, or personal data