CVE-2023-39617 in X5000R
Summary
by MITRE • 08/21/2023
TOTOLINK X5000R_V9.1.0cu.2089_B20211224 and X5000R_V9.1.0cu.2350_B20230313 were discovered to contain a remote code execution (RCE) vulnerability via the lang parameter in the setLanguageCfg function.
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Analysis
by VulDB Data Team • 01/25/2026
The vulnerability identified as CVE-2023-39617 represents a critical remote code execution flaw affecting TOTOLINK X5000R routers running specific firmware versions. This vulnerability resides within the setLanguageCfg function of the device's web interface, where the lang parameter fails to properly validate user input before processing. The flaw allows attackers to inject malicious code that executes with the privileges of the web server process, potentially enabling full system compromise and unauthorized access to network resources. This vulnerability directly maps to CWE-74, which describes improper neutralization of special elements in output used by a downstream component, commonly known as injection flaws.
The technical implementation of this vulnerability stems from insufficient input sanitization within the router's configuration management interface. When users interact with the language settings functionality, the system accepts the lang parameter without adequate validation or filtering mechanisms. This oversight creates an exploitation vector where malicious actors can craft specially formatted input that bypasses normal security controls and executes arbitrary commands on the affected device. The vulnerability is particularly concerning because it operates at the application layer, requiring no physical access or authentication credentials to exploit, making it highly attractive to remote attackers.
From an operational perspective, successful exploitation of this vulnerability could result in complete compromise of the affected router, enabling attackers to establish persistent backdoors, modify network configurations, intercept traffic, or use the device as a pivot point for attacking other systems within the local network. The impact extends beyond individual device compromise to potentially affect entire network infrastructures, especially in enterprise environments where multiple routers may be running vulnerable firmware versions. Network administrators face the challenge of identifying all affected devices and applying patches without disrupting network operations, as these devices often serve as critical network infrastructure components.
Security mitigations for CVE-2023-39617 should prioritize immediate firmware updates from TOTOLINK, as these contain the necessary patches to address the input validation flaw in the setLanguageCfg function. Organizations should also implement network segmentation to limit the potential impact of successful exploitation, deploy intrusion detection systems to monitor for exploitation attempts, and consider disabling unnecessary web management interfaces when possible. The vulnerability aligns with ATT&CK technique T1219, which describes legitimate remote access tools being used for persistence and command execution, making it essential for security teams to monitor for unusual network traffic patterns and unauthorized configuration changes. Additionally, implementing proper input validation controls and adhering to secure coding practices can prevent similar injection vulnerabilities in future development cycles.