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CVE-2026-54403: A malicious actor with access to the network could exploit a Path Traversal vulnerability found in certain dev

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HIGH 8.6REMOTEUPGRADEUPGRADEUPGRADE

CVE-2026-54403 is a high-severity flaw (CVSS 8.6) 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 could exploit a Path Traversal vulnerability found in certain devices running UniFi OS to bypass authentication of such UniFi OS devices or instances.

Why this priority

  • High severity
  • Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score8.6 (High)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance0.8% (top 45%)
CISA exploited listNo
WeaknessCWE-22
Published2026-07-02
Last modified2026-07-10
Publisher (CNA): HackerOne · Vendor: ui

Share: LinkedIn · X · Reddit

Last updated 2026-07-10 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

ui unifi os server UPGRADE
Affected: <= 5.1.15
Fixed in: newer than 5.1.15
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy unifi-os-server || rpm -q unifi-os-server || unifi-os-server --version
2. UPGRADE to newer than 5.1.15 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade unifi-os-server
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade unifi-os-server
Note
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 source NVD · 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-2026-54403?

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-2026-54403 being exploited?

CVE-2026-54403 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-2026-54403 affect?

CVE-2026-54403 affects unifi os server, unifi dream machine firmware, unifi dream machine pro firmware. Severity is high (CVSS 8.6). A malicious actor with access to the network could exploit a Path Traversal vulnerability found in certain devices running UniFi OS to bypass authentication of such UniFi OS devices or instances.

How urgent is CVE-2026-54403?

Priority 49/100. High severity; Remotely exploitable, no login, no user action

Software pages

Ubiquiti vulnerabilities

Related CVEs

References

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