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Known exploited vulnerability

CVE-2026-34909

criticalCVSS 3.1 10.0In CISA KEVEPSS 69%Published · Ubiquiti Inc

The short answer

CVE-2026-34909 affects Ubiquiti Inc UniFi OS Server and is rated critical (CVSS 10.0). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-06-23: attackers are using it, so patch it first. The vendor has linked a patch.

What it is

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.

Weakness: CWE-22.

Severity

10.0 critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Exploited (CISA KEV)

Yes, since Jun 23, 2026

Federal due date Jun 26, 2026

EPSS, next 30 days

69%

Higher than 99% of scored CVEs

How it can be exploited

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
High

What CISA says to do

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…

Affected products

UniFi OS Server, Express, UDM, UDM-Pro, UDM-SE, UDM-Pro-Max, UDM-Beast, EFG, UDW, UDR, UDR7, UDR-5G. NVD's record lists the exact affected versions.

References

Questions

Is CVE-2026-34909 being exploited?

Yes. CISA added CVE-2026-34909 to its Known Exploited Vulnerabilities catalog on 2026-06-23, with a federal remediation due date of 2026-06-26.

How do I fix CVE-2026-34909?

CISA's 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…

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.

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