CVE-2021-20590
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 · uneditedImproper authentication vulnerability in GOT2000 series GT27 model VNC server versions 01.39.010 and prior, GOT2000 series GT25 model VNC server versions 01.39.010 and prior, GOT2000 series GT21 model GT2107-WTBD VNC server versions 01.40.000 and prior, GOT2000 series GT21 model GT2107-WTSD VNC server versions 01.40.000 and prior, GOT SIMPLE series GS21 model GS2110-WTBD-N VNC server versions 01.40.000 and prior and GOT SIMPLE series GS21 model GS2107-WTBD-N VNC server versions 01.40.000 and prior allows a remote unauthenticated attacker to gain unauthorized access via specially crafted packets when the "VNC server" function is used.
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 confidenceImproper authentication vulnerability in the VNC server function of Mitsubishi Electric GOT2000 and GOT SIMPLE series HMI devices allows remote unauthenticated attackers to gain unauthorized access via specially crafted packets. The vulnerability affects GT27 (v01.39.010 and prior), GT25 (v01.39.010 and prior), GT21 models (v01.40.000 and prior), and GS21 models (v01.40.000 and prior).
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<= 01.39.010<= 01.39.010<= 01.40.000<= 01.40.000<= 01.40.000<= 01.40.000CVSS 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
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
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 checksWork through these to decide whether this CVE applies to you.
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Identify the HMI device modelAccess the GOT2000 or GOT SIMPLE device and navigate to the system information or model identification screen. Alternatively, check the physical device label or documentation.Affected if The model is GT27, GT25, GT2107-WTBD, GT2107-WTSD, GS2110-WTBD-N, or GS2107-WTBD-N.
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Check the installed firmware versionOn the HMI device, go to System Settings > Version Information, or access the device via GT Designer3 software and check the firmware version property.Affected if The firmware version is 01.39.010 or prior for GT27/GT25, or 01.40.000 or prior for GT21/GS21 models.
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Verify if the VNC server function is enabledOn the HMI device, navigate to System Settings > Communication Settings > VNC Server, or check the project settings in GT Designer3 for VNC server configuration.Affected if The VNC server function is turned ON or enabled in the device or project configuration.
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Check network accessibility of VNC portsScan the network for open ports typically used by VNC (port 5900 or configured port) on the device IP address using a network scanner or nmap command.Affected if The VNC port is exposed and reachable from network segments that are not trusted or are external.
You are affected if your device is one of the listed models with a vulnerable firmware version AND the VNC server function is enabled and accessible.
Generated from the published advisory. Verify against your own configuration.
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 dataDisable the VNC server function if not required; otherwise, upgrade to vendor-provided fixed versions and restrict network access to the VNC server ports.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20590 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-20590 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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