CVE-2021-27424: GE UR firmware versions prior to version 8.1x shares MODBUS memory map as part of the communications guide
38
Routine
MEDIUM 5.3REMOTEUPGRADEUPGRADEUPGRADE
CVE-2021-27424 is a medium-severity flaw (CVSS 5.3) affecting multilin b30 firmware, multilin b90 firmware, multilin c60 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
GE 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.
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
Published CVE record published
Updated Record last modified
ge multilin b30 firmware UPGRADE
Affected: < 8.10
Fixed in: 8.10
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
ge multilin b90 firmware UPGRADE
Affected: < 8.10
Fixed in: 8.10
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
ge multilin c60 firmware UPGRADE
Affected: < 8.10
Fixed in: 8.10
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
ge multilin c70 firmware UPGRADE
Affected: < 8.10
Fixed in: 8.10
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
ge multilin c95 firmware UPGRADE
Affected: < 8.10
Fixed in: 8.10
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
ge multilin d30 firmware UPGRADE
Affected: < 8.10
Fixed in: 8.10
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
Verify at the official sourceNVD · CVE Program · Report a problem with this page Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2021-27424?
multilin b30 firmware: upgrade to 8.10; multilin b90 firmware: upgrade to 8.10; multilin c60 firmware: upgrade to 8.10. Exact commands for each OS are on this page.
Is CVE-2021-27424 being exploited?
CVE-2021-27424 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2021-27424 affect?
CVE-2021-27424 affects multilin b30 firmware, multilin b90 firmware, multilin c60 firmware. Severity is medium (CVSS 5.3). GE 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.
How urgent is CVE-2021-27424?
Priority 38/100. Remotely exploitable, no login, no user action
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