dbcve.org
Capital VstarApplication · Siemens

CVE-2021-31346

CRITICAL · 9.1 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 →
100/100
Remediation priority · Urgent
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). The total length of an ICMP payload (set in the IP header) is unchecked. This may lead to various side effects, including Information Leak and Denial-of-Service conditions, depending on the network buffer organization in memory. (FSMD-2021-0007)

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

This is an ICMP packet length validation vulnerability in multiple Siemens industrial embedded products. The ICMP payload length field in the IP header is not validated, allowing malformed packets to trigger out-of-bounds memory reads. This can lead to information disclosure (reading adjacent memory contents) or denial-of-service (crashes/memory corruption) depending on how the network buffer is organized in memory.

MitigationApply vendor-supplied firmware updates for all affected products (Capital Embedded AR Classic, PLUSCONTROL, SIMOTICS CONNECT 400). If patches are unavailable, isolate affected devices behind stateful firewalls that can validate ICMP packet lengths and block malformed packets.

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
High
Integrity
None
Availability
High

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

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 the Siemens industrial product
    Query the device's web interface, SNMP, or login via console/SSH to determine the exact product name and firmware version. For Nucleus-based products, check the boot banner or system information pages.
    Affected if The product is one of: Capital Vstar, Nucleus Net, Nucleus Readystart V3/V4, Nucleus Source Code, Apogee Modular Building Controller, Apogee Modular Equipment Controller, or Apogee PXC Compact Firmware.
  2. Verify the firmware version against affected ranges
    Locate the firmware version string in the device's system info, boot logs, or management interface. Compare numerically to: Nucleus Readystart V3 < 2017.02.1, Nucleus Readystart V4 < 4.1.1. For all other listed products, any version is affected.
    Affected if Version is unpatched or matches 'all versions' for the specific product listed.
  3. Confirm ICMP network accessibility
    Send ICMP echo requests (ping) to the device from an external host. Verify the device responds to ICMP. Check any firewall or access control lists that may filter ICMP traffic.
    Affected if The device responds to ICMP echo requests or allows ICMP packets through its network stack.
  4. Check if ICMP processing is enabled in the network stack
    Review the device's network configuration or kernel/ firmware parameters. For embedded systems, examine /proc/sys/net/ipv4/icmp_echo_ignore_all (if accessible) or check the network daemon configuration for ICMP handling modules.
    Affected if ICMP echo processing is not explicitly disabled or filtered at the network boundary.

The environment is affected if the device runs an unpatched Siemens product from the list (any version for most, or specific versions for Nucleus Readystart) AND ICMP traffic can reach the device over the network.

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 vendor-supplied firmware updates for all affected products (Capital Embedded AR Classic, PLUSCONTROL, SIMOTICS CONNECT 400). If patches are unavailable, isolate affected devices behind stateful firewalls that can validate ICMP packet lengths and block malformed packets.

Fix this in Capital Vstar Scoped from the published advisory
  • Consultation8.0 h
  • Implementation4.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,840
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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-2021-31346 in production — separate from our analysis above.

No notes yet

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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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data