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Gt27 FirmwareOperating system · Mitsubishi

CVE-2021-20589

HIGH · 7.5 CVSS v3.1 Published 2021-05-19
Fix available
A fix is available. Upgrade to after 1.250l or later.
See remediation →
84/100
Remediation priority · High
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
Buffer access with incorrect length value vulnerability in GOT2000 series GT27 model communication driver versions 01.19.000 through 01.38.000, GT25 model communication driver versions 01.19.000 through 01.38.000, GT23 model communication driver versions 01.19.000 through 01.38.000 and GT21 model communication driver versions 01.21.000 through 01.39.000, GOT SIMPLE series GS21 model communication driver versions 01.21.000 through 01.39.000, GT SoftGOT2000 versions 1.170C through 1.250L and Tension Controller LE7-40GU-L Screen package data for MODBUS/TCP V1.00 allows a remote unauthenticated attacker to stop the communication function of the products via specially crafted packets.

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

Buffer access with incorrect length value vulnerability in Mitsubishi Electric GOT2000 series and related HMI communication drivers for MODBUS/TCP allows remote unauthenticated attackers to cause a denial of service by sending specially crafted packets that trigger the incorrect length calculation, stopping the communication function.

MitigationUpdate affected communication drivers to versions beyond the vulnerable range (GT27/GT25/GT23: 01.39.000 or later; GT21/GS21: 01.40.000 or later; GT SoftGOT2000: 1.250M or later) and apply any available Tension Controller screen package updates. Implement network segmentation and firewall rules to restrict MODBUS/TCP access to trusted sources as compensating controls if immediate patching is not feasible.

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
Gt27 FirmwareOperating system
Affected:>= 01.19.000, <= 01.38.000
Gt25 FirmwareOperating system
Affected:>= 01.19.000, <= 01.38.000
Gt23 FirmwareOperating system
Affected:>= 01.19.000, <= 01.38.000
Gt21 FirmwareOperating system
Affected:>= 01.21.000, <= 01.39.000
Gs21 FirmwareOperating system
Affected:>= 01.21.000, <= 01.39.000
Gt Softgot2000 FirmwareOperating system
Affected:>= 1.170c, <= 1.250l

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
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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 GOT2000 series model
    Locate the HMI model designation on the physical device or in the system documentation. Common models include GT27, GT25, GT23, GT21, GS21, or GT SoftGOT2000.
    Affected if The model is any of the following: GT27, GT25, GT23, GT21, GS21, or GT SoftGOT2000.
  2. Determine the installed firmware version
    Access the HMI device via Ethernet or USB and navigate to the system settings, or consult the project file exported from GT Designer3. The firmware version is typically displayed in the system information or device properties screen.
    Affected if The firmware version falls within these ranges: GT27/GT25/GT23: 01.19.000 to 01.38.000; GT21/GS21: 01.21.000 to 01.39.000; GT SoftGOT2000: 1.170c to 1.250l.
  3. Confirm MODBUS/TCP communication driver is in use
    Review the GT Designer3 project settings and confirm whether a MODBUS/TCP connection is configured in the communication settings or driver list. Check if MODBUS/TCP is listed as an active communication driver.
    Affected if MODBUS/TCP communication driver is enabled and configured for communication with external devices.
  4. Review system logs for communication failures
    Examine the HMI logs or event records for recent denial of service events or communication interruptions. Look for unexplained communication stoppages that coincide with external MODBUS/TCP traffic.
    Affected if There are unexplained communication stoppages or denial of service events related to MODBUS/TCP.

A system is affected if it uses any of the listed GOT2000 models (GT27/GT25/GT23/GT21/GS21/GT SoftGOT2000) with firmware within the vulnerable version ranges AND has MODBUS/TCP communication enabled.

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 a release after 1.250l
Interim mitigation

Update affected communication drivers to versions beyond the vulnerable range (GT27/GT25/GT23: 01.39.000 or later; GT21/GS21: 01.40.000 or later; GT SoftGOT2000: 1.250M or later) and apply any available Tension Controller screen package updates. Implement network segmentation and firewall rules to restrict MODBUS/TCP access to trusted sources as compensating controls if immediate patching is not feasible.

Fix this in Gt27 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-2021-20589 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