Vulnerability record

CVE-2023-27992

Zyxel Multiple NAS Devices Command Injection Vulnerability

CriticalExploitation confirmedCISA KEV

What should I do?

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it. If you run Multiple Network-Attached Storage (NAS) Devices, fix it now.

CISA required action: Apply updates per vendor instructions.

US federal civilian agencies must remediate by Jul 14, 2023.

Patch status

Official fix available since Sep 30, 2026

Apply the vendor's update to every affected system. Check the fixed-in versions below where known.

Basis: NVD patch reference

Patch or advisory on zyxel.com (opens in a new tab)

Description

The pre-authentication command injection vulnerability in the Zyxel NAS326 firmware versions prior to V5.21(AAZF.14)C0, NAS540 firmware versions prior to V5.21(AATB.11)C0, and NAS542 firmware versions prior to V5.21(ABAG.11)C0 could allow an unauthenticated attacker to execute some operating system (OS) commands remotely by sending a crafted HTTP request.

Source: NIST National Vulnerability Database. Official vulnerability data, reproduced as published.

Affected products

Products affected by this vulnerability, with versions and the source of each entry
Product	Vendor	Source
Multiple Network-Attached Storage (NAS) Devices	Zyxel	KEV

Sources: KEV = CISA Known Exploited Vulnerabilities catalog. Version details have not been published yet.

Intelligence timeline

Developments from the last 30 days, newest first.

CVSS scoredUpdateKEVSep 30, 2026
CVE-2023-27992 scored CVSS 9.8: Zyxel Multiple Network-Attached Storage (NAS) Devices, Zyxel Multiple NAS Devices Command Injection Vulnerability
CISA lists this as exploited in the wild. Unpatched Multiple Network-Attached Storage (NAS) Devices systems are exposed to active attacks now.
Basis: NIST National Vulnerability Database
Patch releasedUpdateKEVSep 30, 2026
Patch released for CVE-2023-27992: Zyxel Multiple Network-Attached Storage (NAS) Devices, Zyxel Multiple NAS Devices Command Injection Vulnerability
An official fix is now available for Zyxel Multiple Network-Attached Storage (NAS) Devices. This vulnerability is being exploited, so apply it promptly.
Basis: NVD patch reference

1 earlier event is available with a subscription. See plans.

Coverage

We have not published a story about this vulnerability yet.

References

zyxel.com https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-pre-authentication-com…
nvd.nist.gov https://nvd.nist.gov/vuln/detail/CVE-2023-27992
cisa.gov https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-27992