What is CVE-2026-34909?

CVE-2026-34909 is Ubiquiti UniFi OS Path Traversal Vulnerability. The supplied enrichment data classifies it as Remote Code Exec mapped to CWE-22 CWE-22.

Which versions are affected?

Affected product and version evidence is listed in the product table above. Current public advisories should be checked for exact version scope before patch targeting is finalized.

Is there active exploitation?

Yes: CISA KEV signal present. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

Is there a public exploit?

9 public PoC repositories reported; 2 marked weaponized in current dataset. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with web/proxy/WAF logs, application logs, network IDS/IPS, EDR process telemetry, host service logs where available. Look for vulnerability-class behavior, product errors, suspicious authentication events, exploit probes, and abnormal process activity based only on evidence that applies to the affected product.

How should teams prioritize it?

Prioritize CVE-2026-34909 using CVSS 10, EPSS 63%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

The supplied mitigation guidance says to apply vendor patches and restrict external exposure until fixed. Fixed-version evidence is listed in the mitigation section above.

Which threat actors are linked publicly?

No public threat actor linkage is confirmed from current sources. Do not attribute exploitation to a threat actor unless the source evidence explicitly supports that linkage.

What should be done in the next 24 hours?

Identify exposed assets running affected vendor/product/version combinations. Treat as emergency remediation because CISA KEV status is present. Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class. Open remediation tickets with affected assets, owners, evidence status, and detection coverage so decisions are traceable.

CISA KEVcriticalRemote Code Execpublic exploit

CVE-2026-34909

Ubiquiti UniFi OS Path Traversal Vulnerability

Q: Is it in CISA KEV?

Yes. The supplied enrichment data lists CVE-2026-34909 in CISA KEV with required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.. KEV status should be monitored because it can change after initial disclosure or after exploitation becomes publicly confirmed.

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.

Published May 22, 2026Updated Jul 23, 2026Sources: NVD, Ubiquiti Inc (CNA), CISA, FIRST EPSS, GitHub, GitHub Security Advisory

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Confirmed

CISA KEV, listed Jun 23, 2026

EPSS

63%

ahead of 99.1% of scored CVEs

Affects

Ubiquiti Inc

32 products listed

CVSS base

critical

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

Active

none · proof-of-concept · active

Automatable

Yes

can an attacker script all four kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

The vendor's own words where we have them.

Upgrade UniFi OS Server to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.

CISA required action

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Federal deadline Jun 26, 2026 — passed 58 days ago

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

Identify exposed assets running affected vendor/product/version combinations.
Treat as emergency remediation because CISA KEV status is present.
Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

Vendor	Product	Versions	Status
Ubiquiti Inc	UniFi OS Server	0 to < 5.0.8	Vulnerable
Ubiquiti Inc	Express	0 to < 4.0.14	Vulnerable
Ubiquiti Inc	UDM	0 to < 5.1.12	Vulnerable
Ubiquiti Inc	UDM-Pro	0 to < 5.1.12	Vulnerable
Ubiquiti Inc	UDM-SE	0 to < 5.1.12	Vulnerable
Ubiquiti Inc	UDM-Pro-Max	0 to < 5.1.12	Vulnerable
Ubiquiti Inc	UDM-Beast	0 to < 5.1.11	Vulnerable
Ubiquiti Inc	EFG	0 to < 5.1.12	Vulnerable
Ubiquiti Inc	UDW	0 to < 5.1.12	Vulnerable
Ubiquiti Inc	UDR	0 to < 5.1.12	Vulnerable
Ubiquiti Inc	UDR7	0 to < 5.1.12	Vulnerable
Ubiquiti Inc	UDR-5G	0 to < 5.1.12	Vulnerable

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Availability

High

Confidentiality

High

Integrity

High

Scope

Changed

Attack Complexity

Low

Attack Vector

Network

Privileges Req

None

User Interaction

None

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Source
10	CVSS 3.1	critical	3.9	6	HackerOne (CNA), Ubiquiti Inc (CNA), GHSA

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

Weakness & attack patterns

CWE-22

Inferred from the weakness class — not observed against this CVE.

CAPEC-242 · Code InjectionCAPEC-35 · Leverage Executable Code in Non-Executable Files

CISA KEV details

CISA lists a CVE here once it has evidence of exploitation against real targets.

CISAThat month →

Listed

Jun 23, 2026

Federal deadline

Jun 26, 2026

passed 58 days ago

Ransomware use

Unknown

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a date to argue against.

Public exploit

Capability, not use: code existing is a different claim from anyone running it.

Repositories

2 of the 5 sampled are weaponized

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

Prioritize edge telemetry for network-reachable UniFi OS Server, Express, UDM, UDM-Pro, UDM-SE, UDM-Pro-Max, UDM-Beast, EFG, UDW, UDR, UDR7, UDR-5G, Express 7, UNVR, UNVR-Pro, UNVR-Instant, UNVR-G2, UNVR-G2-Pro, ENVR, ENVR-Core, UNAS-2, UNAS-4, UNAS-Pro, UNAS-Pro-4, UNAS-Pro-8, UCKP, UCK, UCK-Enterprise, UCG-Ultra, UCG-Max, UCG-Fiber, UCG-Industrial.
Monitor for scanner or exploit-pattern traffic after 9 public PoC repositories were reported.

web/proxy/WAF logsapplication logsnetwork IDS/IPSEDR process telemetryhost service logs

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

2026
Added · CVSS 3.1 10.0 (AV:N)
Jul 23, 2026 · NVD
Added to CISA KEV catalog
Jun 23, 2026 · CISA
Initial · CVE published
May 22, 2026 · NVD
Added · GHSA-95fp-244g-g3vr published (critical)
May 22, 2026 · GitHub Security Advisory

References

7 on the record

community.ui.com/releases/Security-Advisory-Bulletin-064-064/84811c09-4cf4-42ab-bd61-cc994445963b
Patch, Vendor Advisory
www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-34909
US Government Resource
www.pwndefend.com/2026/06/09/cve-2026-34910-exploitation-itw-building-a-botnet-mirai/
Exploit, Third Party Advisory, Vendor Advisory
nvd.nist.gov/vuln/detail/CVE-2026-34909
NVD, Vendor Advisory
github.com/advisories/GHSA-95fp-244g-g3vr
Exploit, Third Party Advisory
www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
US Government Resource
www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
US Government Resource

Elsewhere on this site

Ubiquiti Incevery CVE for this vendor
June 2026what else CISA listed
Remote Code Execsame class
CWE-22other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record1

What should defenders know first?

CVE-2026-34909 is Ubiquiti UniFi OS Path Traversal Vulnerability, a critical vulnerability affecting UniFi OS Server, Express, UDM, UDM-Pro, UDM-SE, UDM-Pro-Max, UDM-Beast, EFG, UDW, UDR, UDR7, UDR-5G, Express 7, UNVR, UNVR-Pro, UNVR-Instant, UNVR-G2, UNVR-G2-Pro, ENVR, ENVR-Core, UNAS-2, UNAS-4, UNAS-Pro, UNAS-Pro-4, UNAS-Pro-8, UCKP, UCK, UCK-Enterprise, UCG-Ultra, UCG-Max, UCG-Fiber, UCG-Industrial from Ubiquiti Inc. The current evidence lists it in CISA KEV, and the exploit status is: Yes: CISA KEV signal present. Public exploit evidence is: 9 public PoC repositories reported; 2 marked weaponized in current dataset. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 10 describes technical severity, while EPSS 63% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.