CVE-2026-54402: A malicious actor with access to the network and low privileges could exploit an Improper Input Validation vul
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CRITICAL 9.9UPGRADEUPGRADEUPGRADE
CVE-2026-54402 is a critical-severity flaw (CVSS 9.9) affecting unifi os server, unifi dream machine firmware, unifi dream machine pro firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
A malicious actor with access to the network and low privileges could exploit an Improper Input Validation vulnerability found in UniFi OS to execute a Command Injection on the host device.
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
ui unifi dream machine firmware UPGRADE
Affected: <= 5.1.15
Fixed in: newer than 5.1.15
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.
ui unifi dream machine pro firmware UPGRADE
Affected: <= 5.1.15
Fixed in: newer than 5.1.15
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.
ui unifi dream machine special edition firmware UPGRADE
Affected: <= 5.1.15
Fixed in: newer than 5.1.15
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.
ui unifi dream machine pro max firmware UPGRADE
Affected: <= 5.1.15
Fixed in: newer than 5.1.15
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.
ui unifi dream machine beast firmware UPGRADE
Affected: <= 5.1.15
Fixed in: newer than 5.1.15
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-2026-54402?
unifi os server: upgrade to newer than 5.1.15; unifi dream machine firmware: upgrade to newer than 5.1.15; unifi dream machine pro firmware: upgrade to newer than 5.1.15. Exact commands for each OS are on this page.
Is CVE-2026-54402 being exploited?
CVE-2026-54402 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-2026-54402 affect?
CVE-2026-54402 affects unifi os server, unifi dream machine firmware, unifi dream machine pro firmware. Severity is critical (CVSS 9.9). A malicious actor with access to the network and low privileges could exploit an Improper Input Validation vulnerability found in UniFi OS to execute a Command Injection on the host device.
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