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Gt21 FirmwareOperating system · Mitsubishielectric

CVE-2023-3373

CRITICAL · 9.1 CVSS v3.1 Published 2023-08-04
Fix available
A fix is available. Upgrade to 01.50.000 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
Predictable Exact Value from Previous Values vulnerability in Mitsubishi Electric Corporation GOT2000 Series GT21 model versions 01.49.000 and prior and GOT SIMPLE Series GS21 model versions 01.49.000 and prior allows a remote unauthenticated attacker to hijack data connections (session hijacking) or prevent legitimate users from establishing data connections (to cause DoS condition) by guessing the listening port of the data connection on FTP server and connecting to it.

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 · moderate confidence

The GOT2000 GT21 and GS21 Series HMI devices contain an FTP server with predictable data connection ports. An unauthenticated remote attacker can guess the listening port for FTP data connections and either hijack the session by intercepting the connection or cause DoS by connecting to the predicted port before legitimate users. This is a classic port prediction vulnerability in the FTP protocol implementation.

MitigationApply vendor firmware updates beyond version 01.49.000 when available. As interim measures, restrict network access to the FTP service via firewalls or network segmentation, and consider disabling FTP if not required or replacing with secure file transfer protocols (SFTP/SCP).

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
Gt21 FirmwareOperating system
Affected:< 01.50.000
Gs21 FirmwareOperating system
Affected:< 01.50.000

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
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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 the HMI device model
    Locate the device nameplate or access the device configuration to confirm whether it is a Mitsubishi Electric GT21 Series or GS21 Series HMI device.
    Affected if Device is a GT21 or GS21 Series model
  2. Check the installed firmware version
    Access the device's system information or firmware update settings via the HMI's built-in web server, or use the GT Designer3/GS Developer software to query the device firmware version. Compare the version number to the affected range (below 01.50.000).
    Affected if Firmware version is below 01.50.000
  3. Confirm FTP server is enabled
    Access the device settings via GT Designer3/GS Developer or the device's web interface. Navigate to the communication or network settings and verify whether the FTP server function is turned on.
    Affected if FTP server is enabled on the device
  4. Check FTP network accessibility
    Use a network scan tool (such as nmap) from an external network segment to attempt a TCP connection to port 21 (FTP control port) on the device IP address. Also verify if the device is directly accessible from untrusted networks.
    Affected if FTP port 21 is reachable from a network where untrusted users could connect

A user is affected if they have a GT21 or GS21 HMI device running firmware below version 01.50.000 with the FTP server enabled and accessible from a network where an unauthenticated attacker could reach the device.

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 01.50.000 or later
Fixed in 01.50.000
Interim mitigation

Apply vendor firmware updates beyond version 01.49.000 when available. As interim measures, restrict network access to the FTP service via firewalls or network segmentation, and consider disabling FTP if not required or replacing with secure file transfer protocols (SFTP/SCP).

Recommended fix High confidence

Firmware version 01.50.000

  1. Identify the current firmware version of the affected Mitsubishi Electric GOT2000 Series GT21 or GOT SIMPLE Series GS21 device
  2. Download the firmware version 01.50.000 or later from the official Mitsubishi Electric support website (www.mitsubishielectric.com)
  3. Follow the manufacturer's firmware upgrade instructions specific to the GT21 or GS21 model
  4. Verify the firmware has been successfully updated to version 01.50.000 or later
  5. Confirm that the FTP server data connection vulnerability is resolved by ensuring predictable port behavior is no longer present

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

Fix this in Gt21 Firmware 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-2023-3373 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