CVE-2023-4474 in NAS326
Summary
by MITRE • 11/30/2023
The improper neutralization of special elements in the WSGI server of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an unauthenticated attacker to execute some operating system (OS) commands by sending a crafted URL to a vulnerable device.
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Analysis
by VulDB Data Team • 12/16/2025
The vulnerability identified as CVE-2023-4474 represents a critical command injection flaw within the Web Server Gateway Interface implementation of Zyxel network-attached storage devices. This issue affects specific firmware versions of both NAS326 and NAS542 models, where the WSGI server fails to properly sanitize user input received through HTTP requests. The flaw stems from inadequate validation and neutralization of special characters in URL parameters, creating an exploitable pathway for remote code execution without authentication requirements. Attackers can leverage this vulnerability by crafting malicious URLs that contain OS command sequences, which the vulnerable server then processes and executes with elevated privileges.
The technical nature of this vulnerability aligns with CWE-77 and CWE-94 classifications, representing improper neutralization of special elements in command contexts and improper neutralization of script-related special elements. The flaw operates at the application layer where HTTP requests are processed through the WSGI interface, making it particularly dangerous as it bypasses traditional authentication mechanisms. The vulnerability allows an unauthenticated remote attacker to execute arbitrary OS commands directly on the affected devices, potentially leading to complete system compromise and unauthorized access to stored data. This type of attack vector falls under ATT&CK technique T1059.001 for command and script interpreter execution, where adversaries leverage web application interfaces to gain system-level control.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass full system compromise capabilities. An attacker could potentially gain persistent access to the NAS devices, access sensitive data stored on the network-attached storage, modify or delete files, and establish backdoors for continued unauthorized access. The affected devices operate in enterprise and home network environments where they often serve as central storage repositories for critical business data or personal information, making the potential impact substantial. The vulnerability's remote exploitability without authentication requirements makes it particularly concerning for organizations that may not properly segment their network infrastructure or maintain up-to-date firmware versions.
Mitigation strategies for CVE-2023-4474 should prioritize immediate firmware updates from Zyxel to address the root cause of the command injection vulnerability. Organizations should implement network segmentation to limit access to affected devices and deploy intrusion detection systems to monitor for suspicious URL patterns and command execution attempts. Network administrators should consider implementing web application firewalls that can detect and block malicious URL parameters before they reach the vulnerable WSGI server. Additional defensive measures include disabling unnecessary web services, restricting network access to affected devices through firewall rules, and conducting comprehensive network scans to identify all potentially vulnerable devices. Regular firmware update policies and security awareness training for system administrators can help prevent exploitation of similar vulnerabilities in the future. The vulnerability demonstrates the critical importance of input validation and proper sanitization of user-supplied data in web application interfaces, particularly in enterprise storage devices that serve as central points of data access and management.