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Modicon M340 Bmxp341000 FirmwareOperating system · Schneider Electric

CVE-2020-7540

CRITICAL · 9.8 CVSS v3.1 Published 2020-12-11
Fix available
A fix is available. Upgrade to 3.3 / 3.30 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 CWE-306: Missing Authentication for Critical Function vulnerability exists in the Web Server on Modicon M340, Legacy Offers Modicon Quantum and Modicon Premium and associated Communication Modules (see security notification for affected versions), that could cause unauthenticated command execution in the controller when sending special HTTP requests.

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

A missing authentication vulnerability (CWE-306) in the Web Server component of Schneider Electric Modicon M340, Modicon Quantum, and Modicon Premium PLCs allows unauthenticated attackers to execute commands on the controller by sending specially crafted HTTP requests. No authentication is required to access this critical function.

MitigationRestrict network access to the PLC web server interface through network segmentation and firewall rules; apply vendor firmware updates when available; monitor for unauthorized HTTP requests to the web server.

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 M340 Bmxp341000 FirmwareOperating system
Affected:< 3.30
Modicon M340 Bmxp342000 FirmwareOperating system
Affected:< 3.30
Modicon M340 Bmxp3420102 FirmwareOperating system
Affected:< 3.30
Modicon M340 Bmxp3420102cl FirmwareOperating system
Affected:< 3.30
Modicon M340 Bmxp342020 FirmwareOperating system
Affected:< 3.30
Modicon M340 Bmxp3420302 FirmwareOperating system
Affected:< 3.30
Modicon M340 Bmxp3420302cl FirmwareOperating system
Affected:< 3.30
Bmxnoe0100 FirmwareOperating system
Affected:< 3.3

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 PLC model and hardware reference
    Locate the PLC nameplate or check system documentation for the exact model number (e.g., Bmxp341000, Bmxp3420102, Bmxnoe0100)
    Affected if Model is any of: Bmxp341000, Bmxp342000, Bmxp3420102, Bmxp3420102cl, Bmxp342020, Bmxp3420302, Bmxp3420302cl, or Bmxnoe0100
  2. Check firmware version
    Access the PLC web interface or use the appropriate engineering software (e.g., Unity Pro, EcoStruxure) to retrieve the firmware version from the controller properties
    Affected if Firmware version is below 3.30 (or below 3.3 for Bmxnoe0100)
  3. Verify web server is enabled
    Check PLC configuration settings or attempt to access the web server HTTP port (typically port 80) on the PLC IP address
    Affected if Web server interface is accessible and enabled on the device
  4. Identify exposed network path
    Review network configuration to determine if the PLC web server is directly accessible from outside the local control network or from untrusted zones
    Affected if PLC web server is reachable from outside the protected control network or from less trusted network zones

The environment is affected if the PLC model is one of the listed variants, the firmware version is below 3.30 (or 3.3), and the web server interface is enabled and accessible.

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.

dbcve · scoped
Upgrade available Upgrade to 3.3 / 3.30 or later
Fixed in 3.33.30
Interim mitigation

Restrict network access to the PLC web server interface through network segmentation and firewall rules; apply vendor firmware updates when available; monitor for unauthorized HTTP requests to the web server.

Recommended fix High confidence

Modicon M340 firmware >= 3.30, Bmxnoe0100 firmware >= 3.3

  1. 1. Backup the current PLC configuration and program to a secure location using Unity Pro or EcoStruxure Control Expert software
  2. 2. Download the firmware version 3.30 (or later) for the specific Modicon M340 model from the official Schneider Electric website (www.se.com) or through their customer support
  3. 3. Connect to the PLC via the programming cable (USB or Ethernet) using EcoStruxure Control Expert (formerly Unity Pro)
  4. 4. In the software, navigate to the PLC settings and locate the firmware update function
  5. 5. Select the downloaded firmware file and initiate the firmware update process
  6. 6. Wait for the firmware upload and installation to complete - do not power off the PLC during this process
  7. 7. After the update completes, verify the firmware version has been updated to 3.30 or later
  8. 8. Restore the backed-up configuration to the PLC
Caveat Review Schneider Electric release notes for any changes in functionality or configuration requirements between your current version and 3.30; industrial PLC firmware upgrades may require revalidation of control programs

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Modicon M340 Bmxp341000 Firmware 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-2020-7540 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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data