Simatic Drive Controller Cpu 1504d Tf FirmwareOperating system · Siemens

CVE-2021-37204

HIGH · 7.5 CVSS v3.1 Published 2022-02-09

Fix available

A fix is available. Upgrade to 2.9.4 / 4.0 or later.

See remediation →

84/100

Remediation priority · High

Remotely reachable No privileges Zero-click Patch available

Official description

NVD · unedited

A vulnerability has been identified in SIMATIC Drive Controller family (All versions < V2.9.2), SIMATIC Drive Controller family (All versions >= V2.9.2 < V2.9.4), SIMATIC ET 200SP Open Controller CPU 1515SP PC (incl. SIPLUS variants) (All versions), SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants) (All versions < V21.9), SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants) (All versions >= V21.9 < V21.9.4), SIMATIC ET 200SP Open Controller CPU 1515SP PC2 Ready4Linux (All versions), SIMATIC S7-1200 CPU family (incl. SIPLUS variants) (All versions < V4.5.0), SIMATIC S7-1200 CPU family (incl. SIPLUS variants) (All versions >= V4.5.0 < V4.5.2), SIMATIC S7-1500 CPU family (incl. related ET200 CPUs and SIPLUS variants) (All versions < V2.9.2), SIMATIC S7-1500 CPU family (incl. related ET200 CPUs and SIPLUS variants) (All versions >= V2.9.2 < V2.9.4), SIMATIC S7-1500 Software Controller (All versions < V21.9), SIMATIC S7-1500 Software Controller (All versions >= V21.9 < V21.9.4), SIMATIC S7-PLCSIM Advanced (All versions < V4.0), SIMATIC S7-PLCSIM Advanced (All versions >= V4.0 < V4.0 SP1), SIPLUS TIM 1531 IRC (All versions < V2.3.6), TIM 1531 IRC (All versions < V2.3.6). An unauthenticated attacker could cause a denial-of-service condition in a PLC when sending specially prepared packet over port 102/tcp. A restart of the affected device is needed to restore normal operations.

Technical summary

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions

NVD · CPE data

Simatic Drive Controller Cpu 1504d Tf FirmwareOperating system

Affected:< 2.9.4

Simatic Drive Controller Cpu 1507d Tf FirmwareOperating system

Affected:< 2.9.4

Simatic Et 200sp Open Controller Cpu 1515sp Pc2 FirmwareOperating system

Affected:all versions

Simatic S7 Plcsim Advanced FirmwareOperating system

Affected:< 4.0= 4.0

Tim 1531 Irc FirmwareOperating system

Affected:>= 2.2

Simatic S7 1500 Software ControllerApplication

Affected:all versions

Simatic S7 1200 Cpu 1211c FirmwareOperating system

Affected:>= 4.5.0, < 4.5.2

Simatic S7 1200 Cpu 1212c FirmwareOperating system

Affected:>= 4.5.0, < 4.5.2

CVSS breakdown

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

dbcve · scoped

Upgrade available Upgrade to 2.9.4 / 4.0 / 4.5.2 or later

Fixed in 2.9.44.04.5.2

Vendor patch cert-portal.siemens.com →

Recommended fix High confidence

Device-specific: S7-1200 to V4.5.2; S7-1500/Drive Controller to V2.9.4; ET200SP Open Controller to V21.9.4; S7-1500 Software Controller to V21.9.4; PLCSIM Advanced to V4.0 SP1; TIM 1531 IRC to V2.3.6

1. Identify the specific Siemens SIMATIC device model and current firmware version from the PLC web interface or TIA Administration console
2. Access the Siemens Industry Online Support portal and navigate to the download section for your specific device
3. Download the latest firmware version as specified in the Siemens security advisory SSA-838121
4. For SIMATIC S7-1200 CPU 1211c/1212c: Upgrade to firmware version 4.5.2
5. For SIMATIC S7-1500 CPU / SIMATIC Drive Controller: Upgrade to firmware version 2.9.4
6. For SIMATIC ET 200SP Open Controller CPU 1515SP PC2: Upgrade to firmware version 21.9.4
7. For SIMATIC S7-1500 Software Controller: Upgrade to firmware version 21.9.4
8. For SIMATIC S7-PLCSIM Advanced: Upgrade to version 4.0 SP1

Caveat Firmware upgrades may require TIA Portal version compatibility; backup PLC 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

Primary sources

cert-portal.siemens.comPatch / commit
cert-portal.siemens.comPatchVendor Advisory
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-37204 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2021-37204?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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

At a glance

A fix existsUpgrade to 2.9.4 / 4.0 or later

Severity 7.5 High

Exploit likelihood EPSS, next 30 days 2.2%

Affects: Simatic Drive Controller Cpu 1504d Tf Firmware

Remediation

A high-priority fix

Get a fix

Estimated effortfrom ~11 hrs

ComplexityModerate

Typical engagementfrom $1,950

What a fix involves

We scope it with you and confirm a fixed quote
A specialist builds a reviewed fix
You deploy it to staging first
Optional re-test once it’s live

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2021-37204 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

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.

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.

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.

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.

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.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Remediation

References