CVE-2023-4473: Zyxel NAS326 Firmware

Critical severity, CVSS 9.8. EPSS: 41.3% chance of exploitation in the next 30 days.

A command injection vulnerability in the web server of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an unauthenticated attacker to execute some operating system (OS) commands by sending a crafted URL to a vulnerable device.

Affected products

• Zyxel NAS326 Firmware: up to and including 5.21\(aazf.14\)c0
• Zyxel NAS542 Firmware: up to and including 5.21\(abag.11\)c0

Published 2023-11-30. Last modified 2026-06-17.