CVE-2023-27992
Zyxel Multiple NAS Devices Command Injection Vulnerability
Zyxel Multiple Network-Attached Storage (NAS) Devices
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.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 23 June 2023. US federal agencies were required to remediate it by 14 July 2023.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 82.3%, which is higher than 99.7% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Frequently asked questions
Is CVE-2023-27992 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2023-27992.
What does CVE-2023-27992 affect?
CVE-2023-27992 affects Zyxel Multiple Network-Attached Storage (NAS) Devices. 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.
How severe is CVE-2023-27992?
CVE-2023-27992 is rated CRITICAL with a CVSS base score of 9.8. EPSS puts the probability of exploitation in the next 30 days at 82.3%, higher than 99.7% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 14 July 2023.
How should organisations respond to CVE-2023-27992?
Apply the vendor patch for Zyxel Multiple Network-Attached Storage (NAS) Devices as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.