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Reachable AssertionWeakness · CWE-617

CVE-2026-4392

MEDIUM · 5.3 CVSS v3.1 Published 2026-05-27
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
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
A vulnerability was detected in TeamSpeak 3 Server up to 3.13.7. This issue affects some unknown processing of the component clientek Handshake Handler. Performing a manipulation of the argument proof results in reachable assertion. Remote exploitation of the attack is possible. Upgrading to version 3.13.8 is capable of addressing this issue. Upgrading the affected component is recommended.

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

A reachable assertion vulnerability exists in the clientek Handshake Handler component of TeamSpeak 3 Server versions up to 3.13.7. By manipulating the 'proof' argument during the client handshake process, a remote attacker can trigger an assertion failure, potentially causing denial of service. The vulnerability is exploitable remotely without authentication.

MitigationUpgrade TeamSpeak 3 Server to version 3.13.8 or later to address this vulnerability. This is a straightforward version update that should be tested to ensure normal server operation after the upgrade.

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

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
None
Integrity
None
Availability
Low

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

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 TeamSpeak 3 Server installation
    Identify the server binary or service running TeamSpeak 3 Server. Common locations include /opt/teamspeak3/ or the working directory where the server was started. Check running processes for ts3server or teamspeak3-server processes.
    Affected if TeamSpeak 3 Server is installed and running on the system.
  2. Determine installed TeamSpeak 3 Server version
    Check the server version by examining the version file typically found in the server directory (version.txt or similar), or query the server via telnet/netcat on the server query port (default 10011) using the 'version' command. Alternatively, check the executable file properties or start-up logs for the version number.
    Affected if The version cannot be determined or is not visible.
  3. Compare version to affected range
    Review the detected version number against the affected range: any version 3.13.7 or earlier is vulnerable. Versions 3.13.8 and later are not affected.
    Affected if The installed version is 3.13.7 or any earlier version (e.g., 3.13.6, 3.13.0, 3.12.x, etc.).
  4. Confirm Handshake Handler is accessible
    Verify that the TeamSpeak 3 Server is accepting client connections on the voice port (default 9987/UDP). If the server is running and accessible over the network, the client handshake handler component is exposed to remote attackers.
    Affected if The server is running and listening for client connections on any reachable network interface.

A system is affected if it runs any TeamSpeak 3 Server version 3.13.7 or earlier that is exposed to network connections, since the vulnerability is remotely exploitable without authentication via the handshake handler.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade TeamSpeak 3 Server to version 3.13.8 or later to address this vulnerability. This is a straightforward version update that should be tested to ensure normal server operation after the upgrade.

Recommended fix High confidence

TeamSpeak 3 Server 3.13.8

  1. Download TeamSpeak 3 Server version 3.13.8 from the official TeamSpeak website or their files repository
  2. Stop the running TeamSpeak 3 Server instance
  3. Replace the existing server files with the new version 3.13.8 files
  4. Restart the TeamSpeak 3 Server service
Caveat Review release notes for any configuration or compatibility changes between 3.13.7 and 3.13.8

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

Have this fixed 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
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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-2026-4392 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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