dbcve.org
Simatic Pcs 7 FirmwareOperating system · Siemens

CVE-2021-31894

HIGH · 8.8 CVSS v3.1 Published 2021-07-13
Fix available
A fix is available. Upgrade to 5.4 / 5.7 or later.
See remediation →
90/100
Remediation priority · Urgent
Zero-click Patch available

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 PCS 7 V8.2 and earlier (All versions), SIMATIC PCS 7 V9.X (All versions < V9.1 SP2), SIMATIC PDM (All versions < V9.2 SP2), SIMATIC STEP 7 V5.X (All versions < V5.7), SINAMICS STARTER (containing STEP 7 OEM version) (All versions < V5.4 SP2 HF1). A directory containing metafiles relevant to devices' configurations has write permissions. An attacker could leverage this vulnerability by changing the content of certain metafiles and subsequently manipulate parameters or behavior of devices that would be later configured by the affected software.

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
How this class of weakness works · CWE-732

A sensitive file, directory, or resource is created with permissions more open than it needs, so unintended users can read or modify it. Attackers look for exactly these loose defaults. Remediation is assigning the minimum permissions required and verifying them at install time and at runtime.

General guidance for the incorrect permission assignment class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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 Pcs 7 FirmwareOperating system
Affected:<= 8.2= 9.0
Simatic Pdm FirmwareOperating system
Affected:all versions
Simatic Step 7 FirmwareOperating system
Affected:>= 5.0, < 5.7
Sinamics Starter FirmwareOperating system
Affected:< 5.4= 5.4

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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

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 5.4 / 5.7 or later
Fixed in 5.45.7
Vendor patch cert-portal.siemens.com →
Recommended fix High confidence

SIMATIC PCS 7: V9.1 SP2 or later; SIMATIC PDM: V9.2 SP2 or later; SIMATIC STEP 7: V5.7 or later; SINAMICS STARTER: V5.4 SP2 HF1 or later

  1. 1. Identify the specific Siemens software product from the list: SIMATIC PCS 7, SIMATIC PDM, SIMATIC STEP 7, or SINAMICS STARTER
  2. 2. Determine the currently installed version of the affected software
  3. 3. Obtain the appropriate upgrade from Siemens: For SIMATIC PCS 7 V8.2 and earlier, upgrade to V9.1 SP2 or later; For SIMATIC PCS 7 V9.0, upgrade to V9.1 SP2 or later; For SIMATIC PDM, upgrade to V9.2 SP2 or later; For SIMATIC STEP 7, upgrade to V5.7 or later; For SINAMICS STARTER, upgrade to V5.4 SP2 HF1 or later
  4. 4. Download the upgrade from Siemens Industry Online Support (support.industry.siemens.com) or through your Siemens account
  5. 5. Before upgrading, back up all existing projects and configurations
  6. 6. Install the upgrade following Siemens installation instructions
  7. 7. After upgrade, verify that the directory permissions have been corrected by reviewing the patch notes in the vendor documentation
Caveat Upgrades to newer versions of industrial control software may require project migration, compatibility checks with connected devices, and staff training on new features; backup all projects before upgrading

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

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950. Get the upgrade done

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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-2021-31894 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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