CVE-2023-39638 in DIR-859 A1
Summary
by MITRE • 09/15/2023
D-LINK DIR-859 A1 1.05 and A1 1.06B01 Beta01 was discovered to contain a command injection vulnerability via the lxmldbc_system function at /htdocs/cgibin.
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Analysis
by VulDB Data Team • 01/25/2026
The CVE-2023-39638 vulnerability affects D-Link DIR-859 routers running firmware versions A1 1.05 and A1 1.06B01 Beta01, representing a critical command injection flaw within the router's web interface management system. This vulnerability resides in the lxmldbc_system function located at /htdocs/cgibin, which serves as a gateway for executing system commands through the web-based administration interface. The flaw allows attackers to inject malicious commands that execute with the privileges of the web server process, potentially compromising the entire network infrastructure. The vulnerability stems from insufficient input validation and sanitization of user-supplied data passed to the system command execution function, creating an avenue for arbitrary code execution.
The technical exploitation of this vulnerability occurs through the web interface where administrators or attackers can manipulate parameters sent to the lxmldbc_system function. When the router processes these parameters without proper sanitization, it directly incorporates user input into system command execution contexts, enabling attackers to inject operating system commands. This command injection vulnerability falls under CWE-77 and CWE-89 categories, representing improper neutralization of special elements used in commands and improper neutralization of special elements used in SQL command contexts respectively, though the specific implementation involves shell command injection. The attack surface is particularly concerning as it allows for complete system compromise through a single vulnerable function call.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass complete network compromise and potential data exfiltration. An attacker who successfully exploits this vulnerability can execute arbitrary commands on the router, potentially leading to persistent backdoor installation, network traffic interception, DNS poisoning, or even lateral movement to other network devices. The vulnerability affects the router's core functionality as it impacts the management interface that administrators rely on for configuration changes, making it particularly dangerous in enterprise environments where these devices serve as primary network gateways. According to ATT&CK framework, this vulnerability maps to T1059.001 (Command and Scripting Interpreter: PowerShell) and T1068 (Exploitation for Privilege Escalation) techniques, as the attack chain involves command injection followed by privilege escalation.
Mitigation strategies for CVE-2023-39638 should prioritize immediate firmware updates from D-Link to address the root cause of the vulnerability. Network administrators should implement network segmentation to limit access to administrative interfaces and employ strict firewall rules to restrict external access to the router management ports. Additional protective measures include disabling unnecessary services, implementing strong authentication mechanisms, and monitoring network traffic for suspicious command execution patterns. The vulnerability highlights the importance of input validation and proper sanitization of all user-supplied data, particularly in web applications that interact with system-level functions. Security professionals should conduct regular vulnerability assessments of network infrastructure and implement network monitoring solutions capable of detecting anomalous command execution patterns that may indicate exploitation attempts. Organizations should also consider implementing network access controls and privileged access management solutions to reduce the attack surface and limit potential damage from successful exploitation.