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CVE-2026-34909 Ubiquiti Inc CVE debrief

Ubiquiti UniFi OS Path Traversal Vulnerability debrief. This critical vulnerability in Ubiquiti UniFi OS requires immediate attention from defenders. The CVE Program and NVD have recorded this vulnerability with a CVSS score of 10. Defenders of Ubiquiti UniFi OS deployments should assess exposure and prioritize patching according to CISA’s BOD 26-04 guidance. The vulnerability allows attackers to traverse the file system, potentially leading to unauthorized access and data breaches. Limited details on exploitation and impact are available, emphasizing the need for prompt mitigation.

Vendor
Ubiquiti Inc
Product
UniFi OS
CVSS
CRITICAL 10
CISA KEV
Listed
Original CVE published
2026-06-23
Original CVE updated
2026-06-23
Advisory published
2026-06-23
Advisory updated
2026-06-23

Who should care

Defenders of Ubiquiti UniFi OS deployments, security teams, and operators should assess exposure and prioritize patching according to CISA’s BOD 26-04 guidance. This includes verifying the presence of affected systems, applying vendor-provided mitigations, and ensuring compliance with CISA’s guidance. The vulnerability's high CVSS score and CISA's designation as a Known Exploited Vulnerability indicate a high risk,

Why it matters

This critical vulnerability in Ubiquiti UniFi OS requires immediate attention from defenders. Although exploitation details are limited, the vulnerability's high CVSS score and CISA's designation as a Known Exploited Vulnerability indicate a high risk. Defenders should verify exposure, apply mitigations, and prioritize patching according to CISA’s BOD 26-04 guidance.

  • Verify and apply vendor-provided mitigations
  • Ensure compliance with CISA’s BOD 26-04 guidance
  • Prioritize patching based on risk assessment

Technical summary

A critical path traversal vulnerability exists in Ubiquiti UniFi OS, allowing attackers to access sensitive files and potentially leading to unauthorized access and data breaches. The CVE Program and NVD have recorded this vulnerability with a CVSS score of 10. This vulnerability requires immediate attention from defenders, who should verify exposure, apply mitigations, and prioritize patching according to CISA’s BOD 26-04 guidance.

Defensive priority

High

Recommended defensive actions

  • Apply mitigations in accordance with vendor instructions
  • Ensure compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk guidance
  • Follow CISA’s Forensics Triage Requirements

Evidence notes

The CISA Known Exploited Vulnerabilities catalog and CVE Program record indicate a critical vulnerability in Ubiquiti UniFi OS. However, details on exploitation and impact are limited.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-34909 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-34909

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-34909 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-34909

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

  • CISA Known Exploited Vulnerabilities catalog

    Publisher, destination, and source semantics verified

    URL: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

    Cybersecurity and Infrastructure Security Agency - Official CISA catalog of vulnerabilities known to be exploited in the wild.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.