dbcve.org
Unifi ProtectApplication · Ui

CVE-2026-21634

MEDIUM · 6.5 CVSS v3.1 Published 2026-01-05
Fix available
A fix is available. Upgrade to 6.2.72 or later.
See remediation →
70/100
Remediation priority · Elevated
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 with access to the adjacent network could overflow the UniFi Protect Application (Version 6.1.79 and earlier) discovery protocol causing it to restart. Affected Products: UniFi Protect Application (Version 6.1.79 and earlier). Mitigation: Update your UniFi Protect Application to Version 6.2.72 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

This is a buffer overflow vulnerability in the UniFi Protect Application's discovery protocol. A malicious actor with access to the adjacent network can send specially crafted packets that overflow the discovery mechanism, causing the application to restart (denial of service).

MitigationUpdate UniFi Protect Application from Version 6.1.79 or earlier to Version 6.2.72 or later to patch the buffer overflow vulnerability in the discovery protocol.

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
Unifi ProtectApplication
Affected:< 6.2.72

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. Locate UniFi Protect installation
    Identify where UniFi Protect is running. On UniFi OS consoles (Dream Machine, Cloud Key), access the controller and note the system. On Linux servers, check for the 'unifi-protect' package or process using 'ps aux | grep -i protect'.
    Affected if UniFi Protect is not installed on the system (not affected)
  2. Retrieve installed version number
    Access the UniFi Protect web interface and navigate to Settings > System > About to view the current version. Alternatively, on UniFi OS use 'ubnt-updater -v' or check the controller status page. Note the exact version string displayed.
    Affected if Cannot determine version or UniFi Protect is not accessible (need to verify version manually)
  3. Compare version to affected range
    Take the retrieved version number and compare it numerically against 6.2.72. For example, version 6.1.79 is less than 6.2.72 and thus affected. Version 6.2.72 or higher is not affected.
    Affected if The installed version is any release below 6.2.72 (for example, 6.1.79, 6.2.0, 6.2.45)
  4. Check if discovery protocol is enabled
    In the UniFi Protect web interface, go to Settings > Network > General or check the discovery/mDNS settings. The vulnerability exists in the discovery mechanism, so verify whether discovery features are active.
    Affected if Discovery protocol is enabled and the version is below 6.2.72 (exploitable condition)
  5. Assess network exposure
    Review network configuration to determine if the UniFi Protect discovery service is reachable from adjacent network segments. The vulnerability requires an attacker on the adjacent network.
    Affected if The discovery port (typically UDP) is exposed to untrusted network segments and version is vulnerable

A system is affected if UniFi Protect is installed with a version lower than 6.2.72 and the discovery protocol is enabled, exposing it to adjacent network attacks.

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 6.2.72 or later
Fixed in 6.2.72
Interim mitigation

Update UniFi Protect Application from Version 6.1.79 or earlier to Version 6.2.72 or later to patch the buffer overflow vulnerability in the discovery protocol.

Recommended fix High confidence

UniFi Protect Application version 6.2.72 or later

  1. Access the UniFi Protect controller or UniFi Network application
  2. Navigate to the UniFi Protect settings
  3. Check the current UniFi Protect Application version
  4. Update UniFi Protect Application to version 6.2.72 or later
  5. Verify the update was successful by checking the version number

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

Fix this in Unifi Protect Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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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-2026-21634 in production — separate from our analysis above.

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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