CVE-2026-71930 in VigorSwitch
Summary
by MITRE • 08/24/2026
Multiple DrayTek VigorSwitch models contain a command injection vulnerability in the setTime function. The vulnerability is caused by insufficient filtering of the username and password fields before command execution. A remote attacker can trigger this vulnerability via crafted input to execute arbitrary commands with root privileges. Exploitation requires valid administrative credentials for the device's web management interface.
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Analysis
by VulDB Data Team • 08/25/2026
The DrayTek VigorSwitch series, a line of managed network switches widely deployed in enterprise and small-to-medium business environments, contains a critical command injection vulnerability within its web-based management interface. This flaw specifically affects the setTime function, which is responsible for configuring the device's system clock via Network Time Protocol or manual input. The root cause lies in insufficient sanitization and validation of user-supplied data before it is passed to underlying operating system commands. Specifically, the username and password fields associated with authentication mechanisms used by this function are not adequately filtered against shell metacharacters or command separators. This lack of proper input validation allows an attacker who has obtained valid administrative credentials for the device's web management interface to inject arbitrary operating system commands into the execution context of the switch.
From a technical perspective, this vulnerability represents a classic instance of improper neutralization of special elements used in an OS command, commonly categorized under CWE-78: Improper Neutralization of Special Elements used in an OS Command. The severity is significantly amplified by the fact that these switches typically run on embedded Linux systems where the web server or management daemon often executes with elevated privileges, including root access. When a remote attacker crafts specific input strings containing command injection payloads within the username or password fields during the time synchronization process, the vulnerable application concatenates this malicious input directly into system calls without escaping special characters such as semicolons, ampersands, or pipes. Consequently, the operating system interprets these injected sequences not as part of a string but as distinct commands to be executed immediately by the shell interpreter running with root-level permissions.
The operational impact of exploiting this vulnerability is severe and comprehensive. An attacker who successfully exploits this flaw gains full control over the affected DrayTek VigorSwitch device at the operating system level. This allows for complete compromise of network integrity, as the attacker can modify routing tables, intercept or manipulate traffic passing through the switch, disable security logging mechanisms, install persistent backdoors, and pivot to other devices on the internal network segment connected via that switch. Furthermore, because administrative credentials are required to trigger this vulnerability, it is classified under privilege escalation scenarios where an authenticated user leverages a flaw to gain higher-level access than intended by their role. In terms of threat modeling, this aligns with MITRE ATT&CK techniques related to Command and Scripting Interpreter abuse, specifically lateral movement or defense evasion depending on the attacker's subsequent actions after gaining root access.
Mitigation strategies must address both immediate remediation and long-term security posture improvements. The primary and most effective mitigation is to apply the official firmware update provided by DrayTek that patches this specific command injection flaw in the setTime function. Organizations should verify their inventory of VigorSwitch models against known affected versions and prioritize patching for devices exposed to untrusted networks or those handling sensitive traffic. In addition to applying vendor-supplied patches, network segmentation is critical; administrative interfaces should be restricted to trusted management VLANs using strict access control lists rather than being accessible from general user subnets. Furthermore, implementing multi-factor authentication for the web interface adds a layer of defense against credential theft, which is the prerequisite vector for this specific vulnerability. Regular audits of configuration settings and monitoring for unusual outbound connections or unexpected system logs can help detect potential exploitation attempts in real-time before significant damage occurs.