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Simatic S7 400h V6 FirmwareOperating system · Siemens

CVE-2021-40368

HIGH · 7.5 CVSS v3.1 Published 2022-04-12
Fix available
A fix is available. Upgrade to 6.0.10 / 10.1 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges 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 S7-400 CPU 412-1 DP V7 (All versions), SIMATIC S7-400 CPU 412-2 DP V7 (All versions), SIMATIC S7-400 CPU 412-2 PN/DP V7 (All versions < V7.0.3), SIMATIC S7-400 CPU 414-2 DP V7 (All versions), SIMATIC S7-400 CPU 414-3 DP V7 (All versions), SIMATIC S7-400 CPU 414-3 PN/DP V7 (All versions < V7.0.3), SIMATIC S7-400 CPU 414F-3 PN/DP V7 (All versions < V7.0.3), SIMATIC S7-400 CPU 416-2 DP V7 (All versions), SIMATIC S7-400 CPU 416-3 DP V7 (All versions), SIMATIC S7-400 CPU 416-3 PN/DP V7 (All versions < V7.0.3), SIMATIC S7-400 CPU 416F-2 DP V7 (All versions), SIMATIC S7-400 CPU 416F-3 PN/DP V7 (All versions < V7.0.3), SIMATIC S7-400 CPU 417-4 DP V7 (All versions), SIMATIC S7-400 H V6 CPU family (incl. SIPLUS variants) (All versions < V6.0.10), SIMATIC S7-410 V10 CPU family (incl. SIPLUS variants) (All versions < V10.1), SIMATIC S7-410 V8 CPU family (incl. SIPLUS variants) (All versions < V8.2.3), SIPLUS S7-400 CPU 414-3 PN/DP V7 (All versions < V7.0.3), SIPLUS S7-400 CPU 416-3 PN/DP V7 (All versions < V7.0.3), SIPLUS S7-400 CPU 416-3 V7 (All versions), SIPLUS S7-400 CPU 417-4 V7 (All versions). Affected devices improperly handle specially crafted packets sent to port 102/tcp. This could allow an attacker to create a Denial-of-Service condition. A restart is needed to restore normal operations.

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-119

The program reads or writes outside the bounds of an allocated buffer, corrupting adjacent memory. With crafted input an attacker can overwrite control data and, with effort, redirect execution to their own code. Remediation ranges from bounds checking and safe library functions to compiler mitigations, usually alongside a careful audit of the surrounding code.

General guidance for the memory buffer bounds error 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 S7 400h V6 FirmwareOperating system
Affected:< 6.0.10
Simatic S7 400 Pn\/dp V7 FirmwareOperating system
Affected:all versions
Simatic S7 410 V8 FirmwareOperating system
Affected:all versions
Simatic S7 410 V10 FirmwareOperating system
Affected:< 10.1

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

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 6.0.10 / 10.1 or later
Fixed in 6.0.1010.1
Vendor patch cert-portal.siemens.com →
Recommended fix High confidence

Upgrade to firmware V6.0.10 (S7-400 H V6), V7.0.3 (S7-400 V7), V8.2.3 (S7-410 V8), or V10.1 (S7-410 V10) as applicable to your specific CPU model

  1. 1. Identify the exact SIMATIC S7 CPU model number and current firmware version by accessing the device via TIA Portal or STEP 7, or checking the device's nameplate/metadata.
  2. 2. Consult the Siemens Product Bulletin (ssa-557541.pdf) to confirm the correct firmware version for your specific CPU model.
  3. 3. Download the firmware update package from the official Siemens Industry Online Support website - use the Siemens Firmware Update Tool appropriate for your CPU.
  4. 4. Create a complete backup of the PLC project, CPU configuration, and all relevant parameters before proceeding.
  5. 5. Establish a reliable Ethernet connection to the CPU and ensure stable power during the update process.
  6. 6. Using the Siemens Firmware Update Tool, upload and install the appropriate firmware version: V6.0.10 for S7-400 H V6, V7.0.3 for S7-400 V7 (if applicable), V8.2.3 for S7-410 V8, or V10.1 for S7-410 V10.
  7. 7. After firmware update completes, verify the new firmware version is correctly reported by the CPU.
  8. 8. Restore the PLC project/configuration from the backup and verify all parameters are correctly applied.
Caveat Firmware updates may require TIA Portal/STEP 7 version compatibility check; some legacy configurations may need review after upgrade

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 $3,200. 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-2021-40368 in production — separate from our analysis above.

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What this is

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