Is CVE-2026-34909 actively exploited?

Yes. Previdian tracks CVE-2026-34909 as a known exploited vulnerability. Confidence is confirmed.

What exploitation activity has Previdian observed?

Previdian has not yet recorded sensor-observed exploitation attempts for CVE-2026-34909. Our sensors continue to monitor for activity targeting this CVE.

Which versions are affected?

CVE-2026-34909 affects Ubiquiti UniFi OS Server and 31 other products. Previdian lists 32 version rows; examples include 0 to < 5.0.8, 0 to < 4.0.14, and 0 to < 5.1.12.

Yes. CVE-2026-34909 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Added to Previdian from a trusted third-party report 2 weeks before CISA listed it.

Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2026-34909

Q: What is CVE-2026-34909?

CVE-2026-34909 is an unauthenticated vulnerability affecting Ubiquiti UniFi OS Server and 31 other products. 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.

Q: How should organizations remediate it?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Q: Is it in CISA KEV?

Yes. CVE-2026-34909 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Added to Previdian from a trusted third-party report 2 weeks before CISA listed it.

UniFi OS Server Path Traversal

Ubiquiti / UniFi OS Server · affected before 5.0.8

Watch CVE-2026-34909 Browse KEV feed

Severity: CVSS 10.0 · Critical
Confidence: Confirmed
Exploit status: Exploited in the wild
EPSS: 1.8%
First observed: —
Last observed: —

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-34909 is an unauthenticated vulnerability affecting Ubiquiti UniFi OS Server and 31 other products. A malicious actor with access to the network could exploit a Path Traversal vulnerability found in UniFi OS...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

Ubiquiti / UniFi OS Server affected before 5.0.8.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

UniFi OS Server Path Traversal

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.

Vendor Product Affected Status

Ubiquiti Inc Affected

UniFi OS Server

Before 5.0.8

Affected

Ubiquiti Inc Affected

Express

Before 4.0.14

Affected

Ubiquiti Inc Affected

UDM

Before 5.1.12

Affected

Ubiquiti Inc Affected

UDM-Pro

Before 5.1.12

Affected

Ubiquiti Inc Affected

UDM-SE

Before 5.1.12

Affected

Ubiquiti Inc Affected

UDM-Pro-Max

Before 5.1.12

Affected

Ubiquiti Inc Affected

UDM-Beast

Before 5.1.11

Affected

Ubiquiti Inc Affected

EFG

Before 5.1.12

Affected

Ubiquiti Inc Affected

UDW

Before 5.1.12

Affected

Ubiquiti Inc Affected

UDR

Before 5.1.12

Affected

Ubiquiti Inc Affected

UDR7

Before 5.1.12

Affected

Ubiquiti Inc Affected

UDR-5G

Before 5.1.12

Affected

Ubiquiti Inc Affected

Express 7

Before 5.1.12

Affected

Ubiquiti Inc Affected

UNVR

Before 5.1.12

Affected

Ubiquiti Inc Affected

UNVR-Pro

Before 5.1.12

Affected

Ubiquiti Inc Affected

UNVR-Instant

Before 5.1.12

Affected

Ubiquiti Inc Affected

UNVR-G2

Before 5.1.12

Affected

Ubiquiti Inc Affected

UNVR-G2-Pro

Before 5.1.12

Affected

Ubiquiti Inc Affected

ENVR

Before 5.1.12

Affected

Ubiquiti Inc Affected

ENVR-Core

Before 5.1.12

Affected

Ubiquiti Inc Affected

UNAS-2

Before 5.1.10

Affected

Ubiquiti Inc Affected

UNAS-4

Before 5.1.10

Affected

Ubiquiti Inc Affected

UNAS-Pro

Before 5.1.10

Affected

Ubiquiti Inc Affected

UNAS-Pro-4

Before 5.1.10

Affected

Ubiquiti Inc Affected

UNAS-Pro-8

Before 5.1.10

Affected

Ubiquiti Inc Affected

UCKP

Before 5.1.12

Affected

Ubiquiti Inc Affected

UCK

Before 5.1.12

Affected

Ubiquiti Inc Affected

UCK-Enterprise

Before 5.1.12

Affected

Ubiquiti Inc Affected

UCG-Ultra

Before 5.1.12

Affected

Ubiquiti Inc Affected

UCG-Max

Before 5.1.12

Affected

Ubiquiti Inc Affected

UCG-Fiber

Before 5.1.12

Affected

Ubiquiti Inc Affected

UCG-Industrial

Before 5.1.12

Affected

Published: 22 May 2026
Exploitation Reported: 09 Jun 2026
Attack vector: Remote
Complexity: Low
Privileges: None
User interaction: None

CVE References

CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2026-34909
community.ui.com/releases/Security-Advisory-Bulletin-064-064/... community.ui.com · CVE Record https://community.ui.com/releases/Security-Advisory-Bulletin-064-064/...

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

Defused Cyber

Recorded 09 Jun 2026

A trusted third party reported exploitation.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access

Source	Added
Defused Cyber First	2026-06-09 07:29 UTC
CISA	2026-06-23 00:00 UTC
CVE	2026-06-23 18:11 UTC
All CISA Advisories	2026-06-23 18:20 UTC
The Hacker News	2026-09-22 11:31 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts: 0; 0; 0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

10.0 Critical

Potential damage if exploited. Separate from whether attackers are using it.

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

EPSS

1.8%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') CWE-22

Recent mention · The Hacker News

22 Sep 2026

Zyxel and Veeam Flaws Under Active Exploitation With Command and SYSTEM Access

Read full advisory

All Mentions

Recent mention · The Hacker News

Zyxel and Veeam Flaws Under Active Exploitation With Command and SYSTEM Access

The Hacker News · 22 Sep 2026

Ravie LakshmananSep 22, 2026Vulnerability / Endpoint Security The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Monday added a now-patched security flaw impacting Zyxel GS1900 series switches to its Known Exploited Vulnerabilities (KEV) catalog, citing evidence of active exploitation. The vulnerability, tracked as CVE-2026-7273 (CVSS score: 8.8), is a stack-based buffer overflow vulnerability that could result in arbitrary operating system (OS) command execution. "A stack-based buffer overflow vulnerability in the CGI program of the Zyxel GS1900 series switch firmware...

Recent mention · GreyNoise

Open Season on Kapibala: Attacker Steals Over 18,000 Government Records Through WordPress Exploitation

GreyNoise · 21 Sep 2026

GreyNoise has been tracking malicious use of an IP address since early June 2026 due to its frequent use in scans and attacks against a variety of technologies. We detail a few of the more notable intrusions we observed including the theft of more than 18,000 sensitive records from a western government.

Recent mention · All CISA Advisories

CISA Adds Four Known Exploited Vulnerabilities to Catalog

All CISA Advisories · 23 Jun 2026

CISA has added four new vulnerabilities to its Known Exploited Vulnerabilities (KEV) Catalog, based on evidence of active exploitation. CVE-2025-67038 Lantronix EDS5000 Code Injection Vulnerability CVE-2026-34908 Ubiquiti UniFi OS Improper Access Control Vulnerability CVE-2026-34909 Ubiquiti UniFi OS Path Traversal Vulnerability CVE-2026-34910 Ubiquiti UniFi OS Improper Input Validation Vulnerability These types of vulnerabilities are frequent attack vectors for malicious cyber actors and pose significant risks to the federal enterprise. Binding Operational Directive (BOD) 26-04:...

Timeline

From disclosure to observed exploitation

22 Sep 2026
11:31 UTC

KEV confirmed by The Hacker News

Exploitation attested by an external source
23 Jun 2026
18:20 UTC

KEV confirmed by All CISA Advisories

Exploitation attested by an external source
23 Jun 2026
18:11 UTC

KEV confirmed by CVE

Exploitation attested by an external source
23 Jun 2026
00:00 UTC

Added to CISA KEV

Listed in the CISA Known Exploited Vulnerabilities catalog
09 Jun 2026
07:29 UTC

Added to Previdian KEV Feed

High-confidence, third-party attested exploitation
22 May 2026
00:43 UTC

CVE published

Vulnerability disclosed publicly
31 Mar 2026
15:00 UTC

CVE ID reserved

Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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Evidence confidence and provenance
First-party sensor telemetry
PoC and scanner references
Affected versions and enrichment
Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-34909

Sample API response

{
  "cve_id": "CVE-2026-34909",
  "confidence": "Confirmed",
  "cvss_score": 10.0,
  "cvss_estimated": false,
  "epss_score": 0.01793,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}

CVE-2026-34909

UniFi OS Server Path Traversal

Tags

CVE References

Exploited in the wild

Known exploited vulnerability sources

Observed signals

Scanner coverage

Virtual patch status

Weaknesses

Zyxel and Veeam Flaws Under Active Exploitation With Command and SYSTEM Access

All Mentions

KEV confirmed by The Hacker News

KEV confirmed by All CISA Advisories

KEV confirmed by CVE

Added to CISA KEV

Added to Previdian KEV Feed

CVE published

CVE ID reserved

Automate this intelligence