CVE-2026-4391Public exploitNetwork attack vector

Unauthenticated server crash via unchecked ECC key length

Published May 27, 2026 · Updated May 27, 2026

Heap-based buffer overflow in TeamSpeak 3 Server 3.13.0 through 3.13.7 allows remote attackers to crash the server. The clientek handshake parser trusts a crafted ASN.1 length in an ECC public key and passes an excessive byte count to a fixed-size big-number import buffer. The path runs before password verification, so no credentials or user interaction are required; demonstrated impact is a reliable process crash.

CVSS severity6.9
Medium
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in TeamSpeak 3 Server 3.13.0 through 3.13.7 allows remote attackers to crash the server. The clientek handshake parser trusts a crafted ASN.1 length in an ECC public key and passes an excessive byte count to a fixed-size big-number import buffer. The path runs before password verification, so no credentials or user interaction are required; demonstrated impact is a reliable process crash.

The record

CVE
CVE-2026-4391
Published
May 27, 2026
Updated
May 27, 2026
Vendor
TeamSpeak Systems, Inc.
Product
TeamSpeak 3 Server
Classifications
CWE-122, CWE-119, 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

5.0VulDBAV:N/AC:L/Au:N/C:N/I:N/A:P
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
5.3VulDBCVSS:3.0/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
5.3VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
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

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Your stack

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