CVE-2021-27424
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 · uneditedGE UR firmware versions prior to version 8.1x shares MODBUS memory map as part of the communications guide. GE was made aware a “Last-key pressed” MODBUS register can be used to gain unauthorized information.
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 confidenceGE UR (Universal Relay) firmware versions prior to 8.1x expose a MODBUS memory map in public documentation that includes a 'last-key pressed' register. This register can be read by unauthorized network attackers to obtain information about keys pressed on the device, leading to potential credential or sensitive data disclosure.
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< 8.10< 8.10< 8.10< 8.10< 8.10< 8.10< 8.10< 8.10CVSS 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
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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 GE Multilin device modelLocate the device label or access the front panel menu to identify if the device is a B30, B90, C60, C70, C95, D30, D60, or F35 model. This information is typically visible on the device nameplate or in the device's web interface or EnerVista configuration software.Affected if The device is any of the following models: B30, B90, C60, C70, C95, D30, D60, or F35.
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Check the installed firmware versionAccess the device firmware version through the web interface (System > Device Information), the front panel menu (Device Status > Firmware Revision), or EnerVista software (Device > Properties). Compare the version number to the affected range.Affected if The firmware version is below 8.10 (for example, 7.x, 8.0x, or any version earlier than 8.10).
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Verify if MODBUS communication is enabledCheck the device configuration via the web interface under Communication > Modbus or through EnerVista software. Confirm whether the MODBUS protocol is enabled in the device settings.Affected if MODBUS is enabled and configured on the device.
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Assess network accessibility of the MODBUS interfaceDetermine if the MODBUS TCP port (typically port 502) is exposed to untrusted networks. Use network scanning tools (such as nmap) to check if port 502 is open and reachable from network segments outside the trusted control network.Affected if The MODBUS interface is reachable from network segments that include untrusted or unauthorized users.
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Inspect the MODBUS register for sensitive data exposureUsing a MODBUS client utility (such as modbus-cli or Simply Modbus), connect to the device and read register addresses documented in the public GE MODBUS memory map. Specifically, attempt to read the 'last-key pressed' register to verify if data is returned.Affected if The MODBUS client can successfully read register values from the device, particularly any register that returns key press or input data.
A user is affected if they have a GE Multilin device (B30, B90, C60, C70, C95, D30, D60, or F35) running firmware version below 8.10 with MODBUS enabled and accessible to unauthorized network attackers.
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.
dbcve · scoped8.10
Upgrade GE UR firmware to version 8.1x or later. Until patched, restrict network access to the MODBUS interface using network segmentation and access controls to limit exposure to authorized personnel only.
Firmware version 8.10 or later (8.1x series)
- Contact GE Grid Solutions to obtain the firmware upgrade to version 8.10 or later for your specific Multilin model (B30, B90, C60, C70, C95, D30, D60, or F35)
- Review the GE firmware upgrade procedure documentation specific to your device
- Schedule a maintenance window to perform the firmware upgrade, following industrial control system change management procedures
- After upgrading, verify that the 'Last-key pressed' MODBUS register is no longer exposed or accessible to unauthorized users
- Confirm the firmware version has been successfully updated to 8.10 or later
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation8.0 h
- Implementation4.0 h
- Testing12.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-27424 — 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-2021-27424 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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- Version or environment caveats, and links to real fixes
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