CVE-2026-71919 in VigorSwitch G2540xs
Summary
by MITRE • 08/24/2026
Multiple DrayTek VigorSwitch models contain a command injection vulnerability in the sysreboot function. The vulnerability is caused by insufficient filtering of the config, act, pathN, and valueN 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 • 08/24/2026
The DrayTek VigorSwitch series of network devices contains a critical security flaw within its system reboot functionality, specifically located in the sysreboot function. This vulnerability stems from an insufficient input validation mechanism that fails to properly sanitize or filter user-supplied data before it is processed for command execution. The affected fields include config, act, pathN, and valueN, which are typically used to configure device settings or trigger administrative actions through the web management interface. Because these parameters are directly concatenated into system commands without adequate escaping or restriction of special characters, they serve as a direct vector for code injection attacks. This architectural weakness allows an attacker who has gained access to the administration panel to manipulate internal shell operations by injecting malicious payloads that bypass intended logic flows.
From a technical perspective, this flaw is classified under CWE-78 Improper Neutralization of Special Elements used in an OS Command commonly known as OS Command Injection. The root cause lies in the application's failure to enforce strict allow-listing or robust escaping strategies for inputs destined for system-level commands. When a remote attacker submits crafted input through these specific fields, the underlying operating system interprets the injected characters not as configuration data but as executable shell instructions. This misinterpretation enables the execution of arbitrary commands with the highest level of privilege available to the web server process, which is typically root on embedded Linux-based network devices. The severity of this issue is compounded by the fact that it affects multiple models within the VigorSwitch lineup, indicating a systemic design flaw in how these devices handle administrative API calls or CGI scripts responsible for system maintenance tasks like rebooting.
The operational impact of exploiting this vulnerability is severe and potentially catastrophic for organizational infrastructure. Since exploitation requires valid administrative credentials, an attacker must first compromise the management interface through weak passwords, credential stuffing, or other authentication bypass techniques. However, once authenticated access is achieved, the ability to execute arbitrary commands with root privileges allows the adversary to fully control the device. This includes modifying network routing tables, installing persistent backdoors, exfiltrating sensitive configuration data containing credentials and encryption keys, or using the switch as a pivot point for lateral movement within the internal network. In critical infrastructure environments where these switches are deployed, such compromise can lead to significant service disruption, data breaches, and loss of integrity across connected systems.
This vulnerability aligns with several tactics in the MITRE ATT&CK framework, particularly T1059 Command and Scripting Interpreter for executing commands via shell injection and T1486 Data Encrypted for Impact if ransomware is deployed following initial access. It also relates to TA0002 Execution as it involves running malicious code on the target system. To mitigate this risk, organizations must ensure that all DrayTek VigorSwitch devices are updated to the latest firmware versions released by the vendor, which typically include patches for such input validation flaws. In cases where immediate patching is not feasible, strict network segmentation should be enforced to isolate management interfaces from untrusted networks. Additionally, enforcing strong, complex administrative passwords and multi-factor authentication can significantly reduce the likelihood of an attacker obtaining the initial credentials required to trigger this command injection vulnerability. Regular security audits and monitoring for anomalous outbound connections or unusual configuration changes are also recommended to detect potential exploitation attempts early.