VulnerabilityAnalyzed

CVE-2023-27992

Zyxel Multiple NAS Devices Command Injection Vulnerability

KEVCRITICAL 9.8EPSS 82.3%

Does this matter?

Known to be exploited in the wild (CISA KEV, CISA remediation deadline 14 July 2023). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.

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.

CVSS 3.1: 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS: 82.26% probability · 100th percentile
Public exploits: None in Exploit-DB
CISA KEV: Listed 23 June 2023 · due 14 July 2023
Weakness: CWE-78
Affected: zyxel/nas326 firmware · zyxel/nas540 firmware · zyxel/nas542 firmware
Source: security@zyxel.com.tw

EPSS trend

EPSS 82.3% since 30 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

CISA notes

Apply updates per vendor instructions. https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-pre-authentication-command-injection-vulnerability-in-nas-products; https://nvd.nist.gov/vuln/detail/CVE-2023-27992

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.