Ubiquiti UniFi OS Improper Access Control
CVE-2026-34908 is a critical-severity improper access control vulnerability in UniFi OS Server from Ubiquiti, with a CVSS 3.1 base score of 10.0 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 5.0.8 as the first without the flaw, so updating UniFi OS Server to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on June 23, 2026, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update UniFi OS Server to 5.0.8 or a later version.
- Update UDM to 5.1.12 or a later version.
- Update UDM-Pro to 5.1.12 or a later version.
- CISA's 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.
- Read the advisory on community.ui.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Ubiquiti | UniFi OS Server | before 5.0.8 | 5.0.8 |
| Ubiquiti | UDM | before 5.1.12 | 5.1.12 |
| Ubiquiti | UDM-Pro | before 5.1.12 | 5.1.12 |
| Ubiquiti | UDM-SE | before 5.1.12 | 5.1.12 |
| Ubiquiti | UDM-Pro-Max | before 5.1.12 | 5.1.12 |
| Ubiquiti | UDM-Beast | before 5.1.11 | 5.1.11 |
| Ubiquiti | EFG | before 5.1.12 | 5.1.12 |
| Ubiquiti | UDW | before 5.1.12 | 5.1.12 |
| Ubiquiti | UDR | before 5.1.12 | 5.1.12 |
| Ubiquiti | UDR7 | before 5.1.12 | 5.1.12 |
| Ubiquiti | UDR-5G | before 5.1.12 | 5.1.12 |
| Ubiquiti | Express 7 | before 5.1.12 | 5.1.12 |
| Ubiquiti | UNVR | before 5.1.12 | 5.1.12 |
| Ubiquiti | UNVR-Pro | before 5.1.12 | 5.1.12 |
| Ubiquiti | UNVR-Instant | before 5.1.12 | 5.1.12 |
| Ubiquiti | UNVR-G2 | before 5.1.12 | 5.1.12 |
| Ubiquiti | UNVR-G2-Pro | before 5.1.12 | 5.1.12 |
| Ubiquiti | ENVR | before 5.1.12 | 5.1.12 |
| Ubiquiti | ENVR-Core | before 5.1.12 | 5.1.12 |
| Ubiquiti | UNAS-2 | before 5.1.10 | 5.1.10 |
| Ubiquiti | UNAS-4 | before 5.1.10 | 5.1.10 |
| Ubiquiti | UNAS-Pro | before 5.1.10 | 5.1.10 |
| Ubiquiti | UNAS-Pro-4 | before 5.1.10 | 5.1.10 |
| Ubiquiti | UNAS-Pro-8 | before 5.1.10 | 5.1.10 |
| Ubiquiti | UCKP | before 5.1.12 | 5.1.12 |
Version data comes from the organisation that assigned the CVE; 35 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H. Scored by CNA (hackerone.com).
Official description
A malicious actor with access to the network could exploit an Improper Access Control vulnerability found in UniFi OS devices to make unauthorized changes to the system.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Access Control
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
How developers prevent this class of flaw
- Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
- Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- Record last changed materially (score, affected products, status or references).
References
Advisories
Third-party and government advisories
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-34908US Government Resource
Technical write-ups (may include proof of concept)
- pwndefend.com/2026/06/09/cve-2026-34910-exploitation-itw-building-a-botnet-mirai/Exploit, Third Party Advisory
Other vulnerabilities in UniFi OS Server
- 10.0 Critical severity
- 9.0 Critical severity
- 9.0 Critical severity
- 9.1 Critical severity
- 9.1 Critical severity
- 9.9 Critical severity
Recent Improper Access Control vulnerabilities
- 7.1 High severity
- 7.5 High severity
- 8.6 High severity
- 7.8 High severity
- 8.1 High severity
- 7.3 High severity
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