dbcve.org
Kazoo ServerApplication · Qnap

CVE-2021-38679

CRITICAL · 9.8 CVSS v3.1 Published 2022-02-11
Fix available
A fix is available. Upgrade to 4.11.22 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable 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
An improper authentication vulnerability has been reported to affect QNAP NAS running Kazoo Server. If exploited, this vulnerability allows attackers to compromise the security of the system. We have already fixed this vulnerability in the following versions of Kazoo Server: Kazoo Server 4.11.22 and 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 · moderate confidence

This is an improper authentication vulnerability in Kazoo Server (a SIP/VoIP server based on Kamailio) running on QNAP NAS devices. The vulnerability allows attackers to bypass authentication mechanisms and compromise system security. With a CVSS score of 9.8, it is exploitable remotely with no user interaction required and no special privileges.

MitigationUpgrade Kazoo Server to version 4.11.22 or later on affected QNAP NAS devices. If immediate patching is not possible, consider restricting network access to the Kazoo Server ports or disabling the service until the update can be applied.

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
Kazoo ServerApplication
Affected:< 4.11.22

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/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. Verify Kazoo Server is installed on the QNAP NAS
    Access the QNAP admin interface and check the installed applications, or use the command line to list installed QPKG packages that include Kazoo or Kazoo Server
    Affected if Kazoo Server appears in the list of installed applications on the QNAP device
  2. Confirm Kazoo Server is currently running
    Check the running processes or services on the QNAP NAS for Kazoo-related processes, or verify the service status through the QNAP interface under App Center > Installed apps
    Affected if Kazoo Server is shown as running or enabled on the NAS
  3. Determine the installed Kazoo Server version
    In the QNAP App Center, click on Kazoo Server and view the version information, or use the QPKG command-line tool to query the installed package version
    Affected if The displayed version number is lower than 4.11.22 or cannot be determined to be 4.11.22 or higher
  4. Check for unauthorized SIP traffic or authentication anomalies
    Review SIP logs or network traffic logs for the Kazoo Server service, looking for successful connections from unexpected sources that may indicate authentication bypass was exploited
    Affected if Unusual SIP authentication patterns or unauthorized access attempts are observed in the logs

A QNAP NAS with Kazoo Server installed and running a version earlier than 4.11.22 is vulnerable to CVE-2021-38679 and should be considered at high risk.

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 4.11.22 or later
Fixed in 4.11.22
Interim mitigation

Upgrade Kazoo Server to version 4.11.22 or later on affected QNAP NAS devices. If immediate patching is not possible, consider restricting network access to the Kazoo Server ports or disabling the service until the update can be applied.

Recommended fix High confidence

Kazoo Server 4.11.22 or later

  1. 1. Identify the current version of Kazoo Server running on the QNAP NAS device
  2. 2. If the installed version is below 4.11.22, plan the upgrade to version 4.11.22 or later
  3. 3. Back up the current Kazoo Server configuration and any critical data
  4. 4. Obtain the Kazoo Server 4.11.22 or later version from QNAP's official download center or update mechanism
  5. 5. Apply the upgrade following QNAP's standard software update procedures for the NAS
  6. 6. After upgrade, verify the Kazoo Server version is 4.11.22 or later
  7. 7. Confirm the service is running and accessible

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

Fix this in Kazoo Server 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

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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-2021-38679 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