CVE-2023-27988 in NAS326
Summary
by MITRE • 05/30/2023
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.
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Analysis
by VulDB Data Team • 12/01/2025
The vulnerability identified as CVE-2023-27988 represents a critical post-authentication command injection flaw within the Zyxel NAS326 network-attached storage device firmware ecosystem. This security weakness specifically affects firmware versions prior to V5.21(AAZF.13)C0, creating a significant attack surface for malicious actors who have already gained administrative access to the device. The flaw resides in the device's handling of user-supplied input within command execution contexts, allowing an authenticated attacker with administrator privileges to inject and execute arbitrary operating system commands remotely. The vulnerability's classification as a post-authentication issue indicates that while initial access requires valid administrative credentials, the subsequent exploitation can occur without requiring additional authentication steps, making it particularly dangerous in environments where administrative accounts might be compromised through credential theft or other means.
The technical implementation of this command injection vulnerability stems from inadequate input validation and sanitization within the firmware's command processing mechanisms. When administrative users interact with certain management interfaces or APIs, the system fails to properly escape or filter user-provided parameters before incorporating them into system commands. This allows an attacker to append malicious commands that get executed with the privileges of the administrative account, potentially enabling full system compromise. The vulnerability operates at the operating system level, meaning successful exploitation could result in complete control over the device's functionality, including access to stored data, modification of system configurations, and potential use as a pivot point for further attacks within the network. This type of vulnerability is categorized under CWE-77 and CWE-88 within the Common Weakness Enumeration framework, specifically relating to command injection flaws that occur when user input is not properly validated or sanitized before being passed to system commands.
The operational impact of CVE-2023-27988 extends beyond simple privilege escalation, as it provides attackers with the capability to execute arbitrary code on the target device with the highest possible privileges. This could enable a wide range of malicious activities including data exfiltration, system modification, or the establishment of persistent backdoors. The remote execution capability means that attackers do not need physical access to the device, potentially allowing for large-scale attacks against multiple devices in a network environment. Organizations relying on Zyxel NAS326 devices for storage and file sharing services face significant risk if they have not updated to the patched firmware version, as the vulnerability could be exploited to gain complete control over critical storage infrastructure. The threat landscape for this vulnerability aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter and T1566.001 for Phishing, as attackers could leverage this weakness to establish persistent access and move laterally within compromised networks.
Organizations should immediately prioritize updating their Zyxel NAS326 devices to firmware version V5.21(AAZF.13)C0 or later to mitigate this vulnerability. The update process should be conducted carefully to avoid potential device bricking, following Zyxel's official documentation and procedures for firmware upgrades. Network administrators should also implement additional monitoring and access controls around administrative accounts, including multi-factor authentication and strict access logging. Security teams should conduct thorough vulnerability assessments to identify any devices running affected firmware versions and ensure that all administrative interfaces are properly secured. The vulnerability demonstrates the importance of maintaining up-to-date firmware in networked storage devices, as these systems often serve as critical infrastructure components that, when compromised, can provide attackers with significant access to organizational data and resources. Regular security assessments and vulnerability management processes should include verification of firmware versions across all networked devices to prevent similar issues from affecting other components of the infrastructure.