CVE-2026-34909
Ubiquiti UniFi OS Path Traversal Vulnerability
Ubiquiti UniFi OS
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.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 23 June 2026. US federal agencies were required to remediate it by 26 June 2026.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 69.2%, which is higher than 99.4% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Frequently asked questions
Is CVE-2026-34909 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2026-34909.
What does CVE-2026-34909 affect?
CVE-2026-34909 affects Ubiquiti UniFi OS. 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.
How severe is CVE-2026-34909?
CVE-2026-34909 is rated CRITICAL with a CVSS base score of 10. EPSS puts the probability of exploitation in the next 30 days at 69.2%, higher than 99.4% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 26 June 2026.
How should organisations respond to CVE-2026-34909?
Apply the vendor patch for Ubiquiti UniFi OS as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.