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Modicon Quantum PlcHardware / appliance · Schneider Electric

CVE-2012-0931

CRITICAL · 9.8 CVSS v3.1 Published 2012-01-28
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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
Schneider Electric Modicon Quantum PLC does not perform authentication between the Unity software and PLC, which allows remote attackers to cause a denial of service or possibly execute arbitrary code via unspecified vectors.

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 Modicon Quantum PLC lacks authentication checks when communicating with Unity software, allowing any remote attacker who can reach the PLC on the network to send commands without credentials. This enables denial of service conditions and potential arbitrary code execution on the PLC device.

MitigationImplement authentication between Unity software and the PLC, or enforce strict network segmentation and access controls to restrict PLC communications to authorized systems only.

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
Modicon Quantum PlcHardware / appliance
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
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 Modicon Quantum PLCs in the environment
    Review network infrastructure inventories, PLC configuration records, or use network scanning tools to discover Modicon Quantum devices. Check device firmware/hardware labels or management interfaces for the Quantum model designation.
    Affected if Any Modicon Quantum PLC is present in the network inventory or discovered on the network.
  2. Verify PLC network accessibility
    Attempt to reach the PLC on its Ethernet/IP or Modbus TCP ports (typically ports 502/tcp, 44818/tcp) from network segments that should not have direct PLC access. Use tools like nmap or netcat to test TCP connectivity to the PLC IP address.
    Affected if The PLC accepts connections from network segments outside of the trusted management zone.
  3. Check Unity software authentication configuration
    Examine the Unity Pro/Unity XL project settings and PLC communication configuration. Look for Module/Remote I/O communication parameters and verify whether any username/password or certificate-based authentication is configured for the connection between the engineering workstation and PLC.
    Affected if The Unity-to-PLC connection has no username, password, or certificate authentication configured in the project settings.
  4. Review network segmentation around the PLC
    Inspect firewall rules, ACLs, or VLAN configurations that govern traffic between the PLC and other network devices. Determine if the PLC is isolated on a dedicated management VLAN or if any host can initiate connections to the PLC.
    Affected if The PLC is on a flat network segment or lacks restrictive access controls allowing unauthorized systems to communicate with it.
  5. Assess PLC communication exposure
    Review PLC configuration files, HMI settings, and network diagrams to determine if the Modbus/TCP or Ethernet/IP ports are bound to all network interfaces versus management-only interfaces. Check if the PLC has enabled broadcast/multicast traffic acceptance.
    Affected if The PLC communication ports are exposed to untrusted network segments or the device accepts unsolicited commands from any source.

If Modicon Quantum PLCs are present and accessible on the network without authentication enforcement between Unity software and the PLC, the environment is affected by this vulnerability.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement authentication between Unity software and the PLC, or enforce strict network segmentation and access controls to restrict PLC communications to authorized systems only.

Fix this in Modicon Quantum Plc Scoped from the published advisory
  • Consultation12.0 h
  • Implementation20.0 h
  • Testing12.0 h
  • Review / QA8.0 h
52.0 hours of engineering $9,240
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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-2012-0931 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