CVE-2026-34909: Ubiquiti UniFi OS Path Traversal Vulnerability
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.
What to do
Treat this as urgent. Identify every affected system, starting with anything internet-facing, and apply the vendor fix or mitigation within days. If you cannot patch quickly, isolate or disable the affected service and watch for signs of compromise.
- Priority
- Act now: Patch or mitigate internet-facing systems within days.
- Severity (CVSS)
- 10 critical (vendor’s score; NVD analysis pending)
- CISA assessment (SSVC)
- actively exploited; attackers can automate it at scale; total control of the affected system
- Exploit probability (EPSS, 30 days)
- 1.8%, higher than 77% of all CVEs
- Added to CISA KEV
- 23 June 2026
- CISA fix-by date
- 26 June 2026 (US federal agencies; a sensible deadline for everyone)
- Ransomware use
- Not known
References
Sources: CISA Known Exploited Vulnerabilities · FIRST Exploit Prediction Scoring System (EPSS) · NIST National Vulnerability Database · CISA Vulnrichment (SSVC), via the CVE Program. This product uses data from the NVD API but is not endorsed or certified by the NVD. Summaries are machine-written from CISA’s description; treat the vendor’s advisory as the authority for fixes.