Threat Intelligence / CVE / CVE-2026-34909

CVE-2026-34909 — Ubiquiti Inc UniFi OS Server

CVSS v3.1 10 (CRITICAL) · EPSS 0.0% (higher than 7.9% of all scored CVEs) · Priority 5.3/10 · Published 2026-05-22

As of 2026-05-22, CVE-2026-34909 is a CRITICAL-severity vulnerability in Ubiquiti Inc UniFi OS Server, CVSS v3.1 10, EPSS 0.0% (7.9th percentile). Threadlinqs Intelligence links 4 tracked threat campaigns to CVE-2026-34909, most recently “CVE-2026-50746: Critical Unauthenticated Command Injection in Ubiquiti UniFi Connect Application (CVSS 10.0)”.

Last updated: 2026-05-22

What is CVE-2026-34909?

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.

The record classifies CVE-2026-34909 under weakness class CWE-22. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 10 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 113 days ago.

Severity and exploitation probability

CVSS v3.1 base score: 10 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS (FIRST): 0.0% probability of exploitation in the next 30 days, higher than 7.9% of all scored CVEs
CISA KEV: Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority: 5.3/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
Published: 2026-05-22

Is CVE-2026-34909 being exploited?

It currently carries a trending score of 9 in the Threadlinqs vulnerability feed.

Affected products and versions

Ubiquiti Inc: UniFi OS Server, Express, UDM, UDM-Pro, UDM-SE, UDM-Pro-Max, UDM-Beast, EFG, UDW, UDR

How to fix CVE-2026-34909

No vendor patch reference has been recorded for CVE-2026-34909 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

Threat activity tracking CVE-2026-34909

4 tracked threats in the Threadlinqs corpus reference CVE-2026-34909, either in the campaign’s CVE list or as an indicator on the campaign record.

CVE-2026-50746: Critical Unauthenticated Command Injection in Ubiquiti UniFi Connect Application (CVSS 10.0) — CRITICAL · 2026-07-10
CISA BOD 26-04: Risk-Based Vulnerability Remediation and CISO Reporting Mandate for FCEB Agencies — MEDIUM · 2026-07-06
UniFi OS Server Pre-Auth RCE Chain (CVE-2026-34908/34909/34910): x-original-uri Auth-Gateway Bypass + package-update Command Injection — CRITICAL · 2026-06-08
Ubiquiti UniFi OS — Three Max-Severity Pre-Auth Vulnerabilities (CVE-2026-34908 / 34909 / 34910) in Security Advisory Bulletin 064 — CRITICAL · 2026-05-22

Sources

Seeded from cveorg and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

community.ui.com

Full detection coverage & IOCs for threats exploiting CVE-2026-34909 are available via the Threadlinqs MCP server (Purple tier). View plans →

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