CVE-2026-4392 TeamSpeak CVE debrief

Who should care

Organizations running TeamSpeak 3 Server versions 3.13.7 or earlier for voice communication services, gaming communities, or enterprise collaboration should prioritize patching. System administrators responsible for voice server infrastructure and security teams monitoring for denial-of-service vulnerabilities in communication platforms should assess exposure.

Technical summary

The vulnerability exists in the clientek handshake handler component of TeamSpeak 3 Server. An attacker can manipulate the `proof` argument during the handshake process to trigger a reachable assertion, resulting in a denial of service condition. The vulnerability is remotely exploitable without authentication requirements. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction (UI:N), with low availability impact (VA:L). The underlying weakness is CWE-617 (Reachable Assertion), indicating that an assert() or similar statement can be triggered by external input.

Defensive priority

medium

Recommended defensive actions

• Upgrade TeamSpeak 3 Server to version 3.13.8 or later
• Review and apply the vendor security advisory TS-SA-2026-001
• Monitor for anomalous connection attempts to the TeamSpeak server handshake endpoint
• Consider network-level access controls to limit exposure of TeamSpeak server management interfaces

Evidence notes

The vulnerability was disclosed on 2026-05-27 with a CVSS 4.0 base score of 6.9 (MEDIUM). The attack vector is network-based with low attack complexity and no required privileges or user interaction. The vulnerability affects availability with low impact but has no impact on confidentiality or integrity. The weakness is categorized as CWE-617 (Reachable Assertion).

Official resources