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Ubb Xg FirmwareOperating system · Ui

CVE-2026-21638

HIGH · 8.8 CVSS v3.1 Published 2026-01-08
Fix available
A fix is available. Upgrade to 1.2.3 / 1.4.2 or later.
See remediation →
93/100
Remediation priority · Urgent
No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A malicious actor in Wi-Fi range of the affected product could leverage a vulnerability in the airMAX Wireless Protocol to achieve a remote code execution (RCE) within the affected product. Affected Products: UBB-XG (Version 1.2.2 and earlier) UDB-Pro/UDB-Pro-Sector (Version 1.4.1 and earlier) UBB (Version 3.1.5 and earlier) Mitigation: Update your UBB-XG to Version 1.2.3 or later. Update your UDB-Pro/UDB-Pro-Sector to Version 1.4.2 or later. Update your UBB to Version 3.1.7 or later.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A vulnerability in the airMAX Wireless Protocol allows an adjacent attacker within Wi-Fi range to execute arbitrary code on affected Ubiquiti wireless bridge devices (UBB-XG, UDB-Pro/UDB-Pro-Sector, UBB). The flaw enables complete device compromise without authentication from the wireless side.

MitigationUpdate affected devices to version 1.2.3 or later (UBB-XG), 1.4.2 or later (UDB-Pro/UDB-Pro-Sector), or 3.1.7 or later (UBB) to patch the protocol vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Ubb Xg FirmwareOperating system
Affected:< 1.2.3
Udb Pro FirmwareOperating system
Affected:< 1.4.2
Udb Pro Sector FirmwareOperating system
Affected:< 1.4.2
Ubb FirmwareOperating system
Affected:< 3.1.7

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the device model
    Locate the physical device or check the device's administrative interface for the exact model name (UBB-XG, UDB-Pro, UDB-Pro-Sector, or UBB). The model is typically displayed on the device label or in the device status page of the airOS management interface.
    Affected if The device is a Ubiquiti UBB-XG, UDB-Pro, UDB-Pro-Sector, or UBB wireless bridge.
  2. Check the installed firmware version
    Access the airOS web interface and navigate to the System tab or use the CLI command 'show version' to retrieve the current firmware version installed on the device.
    Affected if The firmware version is below 1.2.3 for UBB-XG, below 1.4.2 for UDB-Pro or UDB-Pro-Sector, or below 3.1.7 for UBB.
  3. Verify wireless radio is enabled
    In the airOS interface, go to the Wireless tab and confirm that the wireless radio is turned on. Alternatively, check the configuration file or use the CLI command 'wl0radio' or similar to see if the radio interface is active.
    Affected if The wireless interface is enabled. The vulnerability is exploitable from the wireless side, so devices with the wireless radio on are at risk.

A user is affected if they have a UBB-XG, UDB-Pro, UDB-Pro-Sector, or UBB device running firmware below the respective threshold (1.2.3, 1.4.2, or 3.1.7) with the wireless interface enabled.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.2.3 / 1.4.2 / 3.1.7 or later
Fixed in 1.2.31.4.23.1.7
Interim mitigation

Update affected devices to version 1.2.3 or later (UBB-XG), 1.4.2 or later (UDB-Pro/UDB-Pro-Sector), or 3.1.7 or later (UBB) to patch the protocol vulnerability.

Recommended fix High confidence

UBB-XG: 1.2.3+ | UDB-Pro/UDB-Pro-Sector: 1.4.2+ | UBB: 3.1.7+

  1. Identify the specific Ubiquiti device model (UBB-XG, UDB-Pro, UDB-Pro-Sector, or UBB)
  2. Check the current firmware version running on the device via the web UI or CLI
  3. Download the appropriate firmware update from Ubiquiti's official support website
  4. Access the device's administration interface and navigate to the firmware upgrade section
  5. Upload and apply the new firmware version

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Ubb Xg Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-21638 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data