Pre-auth Command Injection in Zyxel NAS (< V5.21) via HTTP
CVE-2023-27992 Published on June 19, 2023
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.
Known Exploited Vulnerability
This Zyxel Multiple NAS Devices Command Injection Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. Multiple Zyxel network-attached storage (NAS) devices contain a pre-authentication command injection vulnerability that could allow an unauthenticated attacker to execute commands remotely via a crafted HTTP request.
The following remediation steps are recommended / required by July 14, 2023: Apply updates per vendor instructions.
Vulnerability Analysis
CVE-2023-27992 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. This vulnerability is known to be actively exploited by threat actors in an automatable fashion. The potential impact of an exploit of this vulnerability is considered to be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.
Weakness Type
What is a Shell injection Vulnerability?
The software constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.
CVE-2023-27992 has been classified to as a Shell injection vulnerability or weakness.
Affected Versions
Zyxel NAS326 firmware:- Version < V5.21(AAZF.14)C0 is affected.
- Version < V5.21(AATB.11)C0 is affected.
- Version < V5.21(ABAG.11)C0 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.