CVE-2026-34909: Ubiquiti UniFi OS Path Traversal Vulnerability

In short

Ubiquiti UniFi OS has a weakness classified as path traversal (CWE-22). CISA added it to its Known Exploited Vulnerabilities catalog on 2026-06-23. NVD lists CVSS 3.1 at 10 CRITICAL.

What it is

“Ubiquiti UniFi OS contains a path traversal vulnerability which could allow a malicious actor with access to the network to access files on the underlying system that could be manipulated to access an underlying account.” — CISA KEV, retrieved 2026-11-01

“A malicious actor with access to the network could exploit a Path Traversal vulnerability found in UniFi OS devices to access files on the underlying system that could be manipulated to access an underlying account.” — NVD, retrieved 2026-11-01

Who is affected

Ubiquiti UniFi OS. NVD lists the following versions as affected:

• Ui Unifi OS Server: before 5.0.8
• Ui Unifi Cloud Gateway Industrial Firmware: before 5.1.12
• Ui Unifi Dream Machine Firmware: before 5.1.12
• Ui Unifi Dream Machine Pro Firmware: before 5.1.12
• Ui Unifi Dream Machine Special Edition Firmware: before 5.1.12
• Ui Unifi Dream Machine Pro Max Firmware: before 5.1.12
• Ui Enterprise Fortress Gateway Firmware: before 5.1.12
• Ui Unifi Dream Wall Firmware: before 5.1.12
• Ui Unifi Dream Router Firmware: before 5.1.12
• Ui Unifi Dream Router 7 Firmware: before 5.1.12
• Ui Unifi Express 7 Firmware: before 5.1.12
• Ui Unifi Network Video Recorder Firmware: before 5.1.12
• Ui Unifi Network Video Recorder Pro Firmware: before 5.1.12
• Ui Unifi Network Video Recorder Instant Firmware: before 5.1.12
• Ui Enterprise Network Video Recorder Firmware: before 5.1.12
• Ui Unifi Cloud Gateway Ultra Firmware: before 5.1.12
• Ui Unifi Cloud Gateway Max Firmware: before 5.1.12
• Ui Unifi Cloud Gateway Fiber Firmware: before 5.1.12
• Ui Unifi Dream Router 5g Max Firmware: before 5.1.12
• Ui Enterprise Network Video Recorder Core Firmware: before 5.1.12
• Ui Unifi Cloud Key Plus Firmware: before 5.1.12
• Ui Unifi Cloudkey Firmware: before 5.1.12
• Ui Unifi Cloudkey Enterprise Firmware: before 5.1.12
• Ui Unifi Network Video Recorder g2 Firmware: before 5.1.12
• Ui Unifi Network Video Recorder g2 Pro Firmware: before 5.1.12
• Ui Unifi Dream Machine Beast Firmware: before 5.1.11
• Ui Unas 2 Firmware: before 5.1.10
• Ui Unas 4 Firmware: before 5.1.10
• Ui Unas Pro Firmware: before 5.1.10
• Ui Unas Pro 4 Firmware: before 5.1.10
• Ui Unas Pro 8 Firmware: before 5.1.10
• Ui Unifi Express Firmware: before 4.0.14

Exploitation status

CISA KEV added: 2026-06-23. Known ransomware campaign use: Not reported by CISA. Due date CISA set for US federal civilian agencies: 2026-06-26.

Scores

NVD CVSS 3.1: 10 CRITICAL; vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H; source [email protected].

EPSS by FIRST: 68.03%; percentile 99.32; score date 2026-10-31. EPSS estimates the probability of exploitation in the next 30 days.

CWE: CWE-22.

Timeline

CISA required action

“Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.” — CISA KEV

What to do

• Confirm whether you run Ubiquiti UniFi OS and which version.
• Apply the vendor update or mitigation in the advisory.
• Follow CISA’s required action.
• Review the vendor guidance on signs of compromise.
• Track the fix through completion.

References

• Patch, Vendor Advisory: https://community.ui.com/releases/Security-Advisory-Bulletin-064-064/84811c09-4cf4-42ab-bd61-cc994445963b
• NVD detail
• CVE.org record
• CISA KEV catalog

Sources and dates

CISA Known Exploited Vulnerabilities Catalog, version 2026.10.30; retrieved 2026-11-01. CISA KEV data: CC0 1.0. No endorsement by CISA.

NVD retrieved: 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

EPSS scores by FIRST; score date 2026-10-31.