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Capital VstarApplication · Siemens

CVE-2021-31344

MEDIUM · 5.3 CVSS v3.1 Published 2021-11-09
Fix available
A fix is available. Upgrade to 4.1.1 / 2017.02.1 or later.
See remediation →
62/100
Remediation priority · Elevated
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 Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic R20-11 (All versions < V2303), PLUSCONTROL 1st Gen (All versions), SIMOTICS CONNECT 400 (All versions < V0.5.0.0), SIMOTICS CONNECT 400 (All versions < V1.0.0.0). ICMP echo packets with fake IP options allow sending ICMP echo reply messages to arbitrary hosts on the network. (FSMD-2021-0004)

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

The vulnerability allows attackers to send ICMP echo (ping) packets with forged or fake IP options to affected Siemens devices. The device processes these packets and responds with ICMP echo replies to arbitrary IP addresses specified by the attacker, rather than just the legitimate source. This enables network reflection/amplification attacks, reconnaissance of internal networks, or firewall bypass by leveraging the trusted position of industrial devices.

MitigationApply available vendor firmware/software updates (SIMOTICS CONNECT 400 to V0.5.0.0 or V1.0.0.0 as appropriate, Capital Embedded AR Classic to V2303 or later). Where updates are unavailable, implement network segmentation and firewall rules to restrict ICMP traffic to/from affected devices, and monitor for suspicious ICMP echo patterns.

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
Capital VstarApplication
Affected:all versions
Nucleus NetApplication
Affected:all versions
Nucleus Readystart V3Application
Affected:< 2017.02.1
Nucleus Readystart V4Application
Affected:< 4.1.1
Nucleus Source CodeApplication
Affected:all versions
Apogee Modular Building Controller FirmwareOperating system
Affected:all versions
Apogee Modular Equiment Controller FirmwareOperating system
Affected:all versions
Apogee Pxc Compact 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
Low
Availability
None

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

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 deployed Siemens products
    Inventory all network devices and embedded systems in the environment. Check device labels, management interfaces, or firmware information for product names: Capital Vstar, Nucleus Net, Nucleus Readystart V3/V4, Nucleus Source Code, Apogee Modular Building Controller, Apogee Modular Equipment Controller, or Apogee PXC Compact.
    Affected if Any of these specific Siemens products are present in the network.
  2. Check Nucleus Readystart V3 version
    Access the device management interface or firmware metadata. Look for version information labeled as 'Nucleus Readystart V3' and compare the full version string to 2017.02.1.
    Affected if The installed version is earlier than 2017.02.1.
  3. Check Nucleus Readystart V4 version
    Access the device management interface or firmware metadata. Look for version information labeled as 'Nucleus Readystart V4' and compare the full version string to 4.1.1.
    Affected if The installed version is earlier than 4.1.1.
  4. Verify ICMP processing is enabled
    Check the network configuration or firewall rules on the device to confirm ICMP echo requests are being processed. On managed switches or routers, use 'show ip interface' or similar commands to inspect ICMP settings.
    Affected if ICMP echo processing is enabled and the device responds to ping requests.
  5. Test for ICMP reflection vulnerability
    Send an ICMP echo request packet to the device with IP options set (such as source routing options or record route) where the destination IP differs from the source. Observe if the device sends an echo reply to an IP address other than the original sender.
    Affected if The device responds with ICMP echo replies to IP addresses other than the original request source.

The environment is affected if any of the listed Siemens products are deployed, especially Nucleus Readystart V3 before 2017.02.1 or V4 before 4.1.1, and the device processes ICMP echo requests with IP options.

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 4.1.1 / 2017.02.1 or later
Fixed in 4.1.12017.02.1
Interim mitigation

Apply available vendor firmware/software updates (SIMOTICS CONNECT 400 to V0.5.0.0 or V1.0.0.0 as appropriate, Capital Embedded AR Classic to V2303 or later). Where updates are unavailable, implement network segmentation and firewall rules to restrict ICMP traffic to/from affected devices, and monitor for suspicious ICMP echo patterns.

Fix this in Capital Vstar Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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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-2021-31344 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
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  • No spam, self-promotion, credentials, or personal data