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Simatic Wincc Runtime AdvancedApplication · Siemens

CVE-2021-27386

HIGH · 7.5 CVSS v3.1 Published 2021-05-12
Fix available
A fix is available. Upgrade to 15.1 / 16 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 HMI Comfort Outdoor Panels V15 7\" & 15\" (incl. SIPLUS variants) (All versions < V15.1 Update 6), SIMATIC HMI Comfort Outdoor Panels V16 7\" & 15\" (incl. SIPLUS variants) (All versions < V16 Update 4), SIMATIC HMI Comfort Panels V15 4\" - 22\" (incl. SIPLUS variants) (All versions < V15.1 Update 6), SIMATIC HMI Comfort Panels V16 4\" - 22\" (incl. SIPLUS variants) (All versions < V16 Update 4), SIMATIC HMI KTP Mobile Panels V15 KTP400F, KTP700, KTP700F, KTP900 and KTP900F (All versions < V15.1 Update 6), SIMATIC HMI KTP Mobile Panels V16 KTP400F, KTP700, KTP700F, KTP900 and KTP900F (All versions < V16 Update 4), SIMATIC WinCC Runtime Advanced V15 (All versions < V15.1 Update 6), SIMATIC WinCC Runtime Advanced V16 (All versions < V16 Update 4), SINAMICS GH150 (All versions), SINAMICS GL150 (with option X30) (All versions), SINAMICS GM150 (with option X30) (All versions), SINAMICS SH150 (All versions), SINAMICS SL150 (All versions), SINAMICS SM120 (All versions), SINAMICS SM150 (All versions), SINAMICS SM150i (All versions). SmartVNC has a heap allocation leak vulnerability in the device layout handler on client side, which could result in a Denial-of-Service condition.

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

A heap allocation memory leak vulnerability exists in the SmartVNC component's device layout handler on the client side of affected Siemens SIMATIC HMI panels, WinCC Runtime Advanced, and SINAMICS drives. The vulnerability can be exploited to cause a Denial-of-Service condition due to uncontrolled memory consumption.

MitigationUpgrade affected devices to V15.1 Update 6 or V16 Update 4 (or later) as specified in Siemens Security Advisory SSA-478529. If patching is not immediately feasible, consider network segmentation to limit exposure to untrusted VNC clients.

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 Wincc Runtime AdvancedApplication
Affected:< 16= 16< 15.1= 15.1
Sinamics Sh150 FirmwareOperating system
Affected:all versions
Sinamics Sm150i FirmwareOperating system
Affected:all versions
Sinamics Gh150 FirmwareOperating system
Affected:all versions
Sinamics Gl150 FirmwareOperating system
Affected:all versions
Sinamics Gm150 FirmwareOperating system
Affected:all versions
Sinamics Sl150 FirmwareOperating system
Affected:all versions
Sinamics Sm120 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
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 installed WinCC Runtime Advanced version
    Open the Windows Programs and Features (or appwiz.cpl), locate Siemens SIMATIC WinCC Runtime Advanced, and note the version number. Alternatively, check the program installation directory for version information.
    Affected if The installed version is 15.1 or any version below 16 (including 15.1 and all versions less than 15.1).
  2. Check SINAMICS device firmware versions
    Connect to the SINAMICS drive device via its web interface, TIA Portal, or STARTER/SINAMICS Startdrive software and retrieve the firmware version information from the device properties.
    Affected if The device is a Sinamics Sh150, Sm150i, Gh150, Gl150, Gm150, Sl150, or Sm120 with any firmware version installed.
  3. Verify SmartVNC client listener status
    On the HMI panel or WinCC Runtime Advanced system, check if the SmartVNC server/client component is configured to accept connections. This is typically found in the runtime settings, VNC server configuration, or HMI project settings under remote access or VNC settings.
    Affected if SmartVNC is enabled and accepting VNC connections, making the device vulnerable to malicious VNC servers that can trigger the memory leak.

A user is affected if they run WinCC Runtime Advanced versions 15.1 or 16, or any SINAMICS drive model Sh150, Sm150i, Gh150, Gl150, Gm150, Sl150, or Sm120 with SmartVNC client functionality exposed to untrusted VNC servers.

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 15.1 / 16 or later
Fixed in 15.116
Interim mitigation

Upgrade affected devices to V15.1 Update 6 or V16 Update 4 (or later) as specified in Siemens Security Advisory SSA-478529. If patching is not immediately feasible, consider network segmentation to limit exposure to untrusted VNC clients.

Fix this in Simatic Wincc Runtime Advanced Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2021-27386 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