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Logo\! Cmr2020 FirmwareOperating system · Siemens

CVE-2021-37186

MEDIUM · 5.4 CVSS v3.1 Published 2021-09-14
Fix available
A fix is available. Upgrade to 2.2 / 4.0.9 or later.
See remediation →
59/100
Remediation priority · Elevated
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 LOGO! CMR2020 (All versions < V2.2), LOGO! CMR2040 (All versions < V2.2), SIMATIC RTU3010C (All versions < V4.0.9), SIMATIC RTU3030C (All versions < V4.0.9), SIMATIC RTU3031C (All versions < V4.0.9), SIMATIC RTU3041C (All versions < V4.0.9). The underlying TCP/IP stack does not properly calculate the random numbers used as ISN (Initial Sequence Numbers). An adjacent attacker with network access to the LAN interface could interfere with traffic, spoof the connection and gain access to sensitive information.

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

A detailed technical summary for this CVE is being prepared.

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
Logo\! Cmr2020 FirmwareOperating system
Affected:< 2.2
Logo\! Cmr2040 FirmwareOperating system
Affected:< 2.2
Simatic Rtu3010c FirmwareOperating system
Affected:< 4.0.9
Simatic Rtu3030c FirmwareOperating system
Affected:< 4.0.9
Simatic Rtu3031c FirmwareOperating system
Affected:< 4.0.9
Simatic Rtu3041c FirmwareOperating system
Affected:< 4.0.9

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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

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

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 2.2 / 4.0.9 or later
Fixed in 2.24.0.9
Vendor patch cert-portal.siemens.com →
Recommended fix High confidence

LOGO! CMR2020/CMR2040: V2.2 | SIMATIC RTU3010C/3030C/3031C/3041C: V4.0.9

  1. 1. Identify the exact model and current firmware version of the affected Siemens device (LOGO! CMR2020, LOGO! CMR2040, SIMATIC RTU3010C, RTU3030C, RTU3031C, or RTU3041C)
  2. 2. Download the latest firmware update from Siemens Industry Online Support (support.industry.siemens.com) or the official patch document at https://cert-portal.siemens.com/productcert/pdf/ssa-316383.pdf
  3. 3. Review the firmware upgrade instructions in the Siemens documentation for your specific device model
  4. 4. Back up the current device configuration according to Siemens backup procedures
  5. 5. Ensure the device is connected to a stable power source during the firmware update process
  6. 6. Upload and install the firmware update via the device's web interface, TIA Portal, or the appropriate Siemens management tool
  7. 7. Verify the firmware version has been updated to the fixed release (V2.2 for CMR devices, V4.0.9 for RTU devices)
  8. 8. Restore the device configuration from the backup if needed
Caveat Review Siemens release notes for any configuration or compatibility changes between your current version and the fixed version 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 $1,600. 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-2021-37186 in production — separate from our analysis above.

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  • Version or environment caveats, and links to real fixes
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