CVE-2023-5593: Zyxel Secuextender SSL VPN

High severity, CVSS 7.8. EPSS: 0.2% chance of exploitation in the next 30 days.

The out-of-bounds write vulnerability in the Windows-based SecuExtender SSL VPN Client software version 4.0.4.0 could allow an authenticated local user to gain a privilege escalation by sending a crafted CREATE message.

Affected products

• Zyxel Secuextender SSL VPN: version 4.0.4.0 only

Published 2023-11-20. Last modified 2026-06-17.