dbcve.org
Sinamics Sl150 FirmwareOperating system · Siemens

CVE-2021-27388

CRITICAL · 9.8 CVSS v3.1 Published 2021-06-15
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
SINAMICS medium voltage routable products are affected by a vulnerability in the Sm@rtServer component for remote access that could allow an unauthenticated attacker to cause a denial-of-service condition, and/or execution of limited configuration modifications and/or execution of limited control commands on the SINAMICS Medium Voltage Products, Remote Access (SINAMICS SL150: All versions, SINAMICS SM150: All versions, SINAMICS SM150i: All versions).

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 critical vulnerability in the Sm@rtServer component of SINAMICS medium voltage products (SL150, SM150, SM150i) allows unauthenticated remote attackers to cause denial-of-service conditions and execute limited configuration modifications and control commands. The CVSS 9.8 score reflects the critical nature of unauthenticated remote code impact on industrial control equipment.

MitigationImplement network segmentation to isolate the Sm@rtServer from untrusted networks, apply compensating controls such as firewall rules restricting access to authorized IPs only, and contact Siemens for vendor-specific patches or guidance on disabling the Sm@rtServer if remote access is not required.

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
Sinamics Sl150 FirmwareOperating system
Affected:all versions
Sinamics Sm150 FirmwareOperating system
Affected:all versions
Sinamics Sm150i FirmwareOperating system
Affected:all versions

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 Sinamics device model
    Locate the device nameplate, HMI display, or engineering software project to confirm the exact model (SL150, SM150, or SM150i). Cross-reference with procurement documentation if needed.
    Affected if The model is any variant of SL150, SM150, or SM150i - all versions of these products are affected.
  2. Confirm Sm@rtServer component presence
    Access the Sinamics HMI or engineering tool (e.g., SINAMICS Startdrive in TIA Portal) and navigate to the communication or server settings to determine if Sm@rtServer is installed or enabled.
    Affected if Sm@rtServer is present and enabled on the device.
  3. Check Sm@rtServer network listening status
    From an engineering workstation on the same network segment, use standard network scanning tools (such as Nmap) to probe the device IP for open ports associated with Sm@rtServer communication (consult device documentation for specific port numbers if available).
    Affected if The device has Sm@rtServer ports open and accepting connections from untrusted network segments.
  4. Review network exposure
    Examine network firewall rules, VLAN configurations, or DMZ placements to determine whether Sm@rtServer is accessible from outside the trusted engineering or control network.
    Affected if Sm@rtServer can be reached from untrusted network zones or external IP addresses.

If the device is any Sinamics SL150, SM150, or SM150i and Sm@rtServer is enabled and network-accessible, the environment is affected by CVE-2021-27388.

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

Implement network segmentation to isolate the Sm@rtServer from untrusted networks, apply compensating controls such as firewall rules restricting access to authorized IPs only, and contact Siemens for vendor-specific patches or guidance on disabling the Sm@rtServer if remote access is not required.

Fix this in Sinamics Sl150 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-2021-27388 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