CVE-2026-4392Public exploitNetwork attack vector

Unauthenticated server crash via omitted handshake proof

Published May 27, 2026 · Updated May 27, 2026

Improper input validation in TeamSpeak 3 Server 3.13.7 and earlier allows remote attackers to crash the server before authentication. During the clientek handshake step, the server uses a missing required proof parameter without validating its presence, reaches a failing assertion, and terminates on SIGABRT. The step precedes authentication and password verification, so remote attackers can reliably interrupt service even when a server password is configured.

CVSS severity7.5
High
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper input validation in TeamSpeak 3 Server 3.13.7 and earlier allows remote attackers to crash the server before authentication. During the clientek handshake step, the server uses a missing required proof parameter without validating its presence, reaches a failing assertion, and terminates on SIGABRT. The step precedes authentication and password verification, so remote attackers can reliably interrupt service even when a server password is configured.

The record

CVE
CVE-2026-4392
Published
May 27, 2026
Updated
May 27, 2026
Vendor
TeamSpeak Systems, Inc.
Product
TeamSpeak 3 Server
Classifications
CWE-617, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.13.0
  2. Affected versionversion=3.13.1
  3. Affected versionversion=3.13.2
  4. Affected versionversion=3.13.3
  5. Affected versionversion=3.13.4
  6. Affected versionversion=3.13.5
  7. Affected versionversion=3.13.6
  8. Affected versionversion=3.13.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

TeamSpeak Systems, Inc. · TeamSpeak 3 Serverversion=3.13.0; version=3.13.1; version=3.13.2; version=3.13.3; version=3.13.4; version=3.13.5; version=3.13.6; version=3.13.7

Published CVSS scores

5.3VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
7.5modzeroCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.9VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
7.5TeamSpeakCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0VulDBAV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-617Reachable Assertion
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo