CVE-2026-34908: Ubiquiti UniFi OS Improper Access Control Vulnerability

What it is

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.

Description quoted from the CVE record (assigned by hackerone, published 2026-05-22).

Weakness: CWE-284 Improper Access Control - Generic

How it can be exploited

Exploitable over the network with low attack complexity needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: total.

On CISA KEV since

2026-06-23

US federal deadline

2026-06-26

Ransomware use

Not known

Public exploit evidence (Exploit Observer)

Also known as: BDU:2026-07800, EUVD-2026-31383, GHSA-p8c5-xwrc-584f

VEDAS cluster: VEDAS:FRANGEFROSTBITE

Exploit Observer links 7 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (7)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

• Nuclei template: https://raw.githubusercontent.com/projectdiscovery/nuclei-templates/main/http/cves/2026/CVE-2026-34908.yaml
• Code repository: https://github.com/bishopfox/cve-2026-34908-check
• Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/nuclei/2026/CVE-2026-34908.yaml
• Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/nuclei/2026/CVE-2026-34908.yaml
• Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/suricata/2026/CVE-2026-34908.rules
• Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/suricata/2026/CVE-2026-34908.rules
• Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/suricata/2026/CVE-2026-34908.rules

Research and write-ups (1)

• Research or write-up: https://cveplayground.com/blog/cve-2026-34908-unifi-os-auth-bypass-uri-normalization-rce

Vulnerability databases and vendor advisories (4)

Catalogue entries, not exploit evidence.

• Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2026-31383
• Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-p8c5-xwrc-584f
• Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-34908
• Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-34908

4 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS

0.883
very likely to be attacked soon

VEDAS

0.984
strong exploit evidence

On CISA KEV

Yes, since 2026-06-23

Detection rule

Nuclei · Suricata

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.

Who is affected

11 more products are listed in the CVE record.

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: ubiquiti_networks unifi_os_server, ui unas_2_firmware, ui unas_4_firmware, ui unas_pro_4_firmware, ui unas_pro_8_firmware, ui unas_pro_firmware, ui unifi_express_7_firmware, ui unifi_os_server.

How to fix it

Fixed versions stated in the CVE record: 5.0.8, 5.1.12, 5.1.11, 5.1.10.

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.

Vendor guidance:

• https://community.ui.com/releases/Security-Advisory-Bulletin-064-064/84811c09-4cf4-42ab-bd61-cc994445963b
• https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
• https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
• https://nvd.nist.gov/vuln/detail/CVE-2026-34908

How to detect it

Nuclei template (active check)

UniFi OS - Authentication Bypass

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.

Name and description quoted from the template, written by VEDAS.

The template sends 3 requests (GET /, GET /proxy/users/api/v2/ucs/update/latest_package, GET /api/auth/validate-sso/..%2f..%2f..%2fproxy/users/api/v2/ucs/update...); it decides using dsl matchers. Severity in the template: critical. Marked as not yet verified against a live vulnerable target.

Run it against a host you own or are authorised to test:

nuclei -u https://your-host -t CVE-2026-34908.yaml

id: CVE-2026-34908

info:
  name: "UniFi OS - Authentication Bypass"
  author: vedas-arpsyndicate
  severity: critical
  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.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2026-34908&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=unifi&match=exact
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
    cvss-score: 10.0
    cve-id: CVE-2026-34908
    cwe-id: CWE-284
  metadata:
    verified: false
  tags: cve,cve2026,unifi,ubiquiti,auth-bypass,traversal,kev,unauth,vkev
flow: http(1) && http(2) && http(3)

http:
  - raw:
      - |
        GET / HTTP/1.1
        Host: {{Hostname}}

    host-redirects: true
    max-redirects: 2
    matchers:
      - type: dsl
        dsl:
          - "contains_any(to_lower(body), 'unifi', 'ubiquiti', 'ubnt')"
        internal: true

  - raw:
      - |
        GET /proxy/users/api/v2/ucs/update/latest_package HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - "status_code == 401 || status_code == 403"
        internal: true

  - raw:
      - |
        GET /api/auth/validate-sso/..%2f..%2f..%2fproxy/users/api/v2/ucs/update/latest_package HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - "status_code == 200"
          - "contains_all(body, 'pkg_name required', 'CODE_SYSTEM_ERROR')"
        condition: and

CVE-2026-34908.yaml on GitHub

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2026-34908 UniFi OS - Authentication Bypass. Add them to your Suricata rule set and reload.

alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2026-34908 UniFi OS - Authentication Bypass"; flow:established,to_server; http.uri; content:"..%2f"; nocase; fast_pattern; classtype:web-application-attack; reference:cve,CVE-2026-34908; reference:url,https://www.exploit.observer/?keyword=CVE-2026-34908&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=unifi&match=exact; sid:1011590; rev:1;)

CVE-2026-34908.rules on GitHub

References

Exploits and technical analysis

• https://www.pwndefend.com/2026/06/09/cve-2026-34910-exploitation-itw-building-a-botnet-mirai/ (third-party-advisory)

Government sources

• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-34908 (government-resource)

Other references

• https://community.ui.com/releases/Security-Advisory-Bulletin-064-064/84811c09-4cf4-42ab-bd61-cc994445963b

Other databases

• CVE record (cve.org)
• NVD
• Exploit Observer

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.