CVE-2023-27988: Zyxel NAS326 Firmware

High severity, CVSS 7.2. EPSS: 1.4% chance of exploitation in the next 30 days.

The post-authentication command injection vulnerability in the Zyxel NAS326 firmware versions prior to V5.21(AAZF.13)C0 could allow an authenticated attacker with administrator privileges to execute some operating system (OS) commands on an affected device remotely.

Affected products

• Zyxel NAS326 Firmware: before 5.21\(aazf.13\)c0 (fixed in 5.21\(aazf.13\)c0)
• Zyxel NAS540 Firmware: before 5.21\(aatb.10\)c0 (fixed in 5.21\(aatb.10\)c0)
• Zyxel NAS542 Firmware: before 5.21\(abag.10\)c0 (fixed in 5.21\(abag.10\)c0)

Published 2023-05-30. Last modified 2026-06-17.