CVE-2026-4390Public exploitNetwork attack vector

Remote server crash via resend-queue dangling pointer

Published May 27, 2026 · Updated May 27, 2026

Heap use-after-free in TeamSpeak 3 Server 3.13.0 through 3.13.7 allows remote attackers to crash the server via UDP port 9987. A race between duplicate clientinit packets lets process_resend_queue free a ResendingPacket after a failed client lookup while its acknowledgment-window pointer remains reachable. No account is required, but the packets must reach UDP 9987 and win the narrow handshake race; a later acknowledgment dereferences the dangling pointer and terminates the service.

CVSS severity5.3
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap use-after-free in TeamSpeak 3 Server 3.13.0 through 3.13.7 allows remote attackers to crash the server via UDP port 9987. A race between duplicate clientinit packets lets process_resend_queue free a ResendingPacket after a failed client lookup while its acknowledgment-window pointer remains reachable. No account is required, but the packets must reach UDP 9987 and win the narrow handshake race; a later acknowledgment dereferences the dangling pointer and terminates the service.

The record

CVE
CVE-2026-4390
Published
May 27, 2026
Updated
May 27, 2026
Vendor
TeamSpeak Systems, Inc.
Product
TeamSpeak 3 Server
Classifications
CWE-416, 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

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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

5.4VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
5.5VulDBAV:N/AC:L/Au:S/C:N/I:P/A:P
5.3VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

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.

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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-416Use After Free
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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