CVE-2026-71925 in VigorSwitch G2540xs
Summary
by MITRE • 08/24/2026
Multiple DrayTek VigorSwitch models contain a command injection vulnerability in the getDetail 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 • 08/24/2026
The identified security flaw resides within the getDetail function of multiple DrayTek VigorSwitch models, representing a critical command injection vulnerability that compromises the integrity and availability of network infrastructure devices. This specific weakness stems from insufficient input validation and sanitization mechanisms applied to the username and password fields prior to their use in system-level operations. When these credentials are processed by the device's firmware, they are passed directly into shell commands without adequate filtering for special characters or metacharacters that could alter command logic. Consequently, an attacker who possesses valid administrative credentials can inject malicious payloads through these input vectors, effectively bypassing intended security controls to execute arbitrary operating system commands with root privileges on the managed switch.
From a technical perspective, this vulnerability aligns closely with CWE-78 Improper Neutralization of Special Elements used in an OS Command and CWE-20 Improper Input Validation. The core issue is not authentication failure but rather the lack of robust encoding or escaping procedures for user-supplied data before it interacts with the underlying operating system shell. In many embedded network devices, administrative interfaces often rely on backend scripts that construct command lines dynamically based on form inputs. If these scripts do strictly enforce a whitelist approach to allowed characters or properly escape dangerous symbols such as semicolons, pipes, or backticks, an authenticated user can manipulate the execution flow of these commands. This allows for remote code execution at the highest privilege level available within the device's environment, which typically includes root access in Linux-based embedded systems used by networking hardware vendors.
The operational impact of this vulnerability is severe due to its potential for complete system compromise and lateral movement within a network segment. Although exploitation requires valid administrative credentials, this does not significantly mitigate the risk as credential theft via phishing, brute force attacks against weak passwords, or exposure in configuration backups are common occurrence scenarios. Once an attacker achieves root-level command execution on a managed switch, they can modify routing tables to facilitate traffic interception and man-in-the-middle attacks, disable logging mechanisms to cover their tracks, install persistent backdoors for long-term access, or pivot into other connected network segments that rely on the compromised device for connectivity control. This effectively turns a standard Layer 2 switching device into an active weapon within the enterprise network architecture.
In terms of threat modeling and adversary behavior, this vulnerability maps directly to MITRE ATT&CK technique T1059 Command and Scripting Interpreter under the Execution tactic, specifically involving shell commands like /bin/sh or bash. Furthermore, because it involves modifying system configurations and potentially disabling security features, it relates to Defense Evasion techniques such as T1562 Impair Defenses. The ability to execute arbitrary commands with root privileges also facilitates Privilege Escalation if the initial access was gained through a lower-privileged account that somehow obtained sufficient permissions to trigger this specific function, although in this case, administrative credentials are explicitly required for exploitation.
Mitigation strategies must prioritize immediate patching and configuration hardening. DrayTek has released firmware updates addressing these input validation flaws; administrators should verify their current firmware version against vendor advisories and apply the latest patches immediately. In environments where updating is not feasible due to operational constraints, network segmentation becomes critical. The affected switches should be isolated in a management VLAN with strict access control lists that restrict administrative interface access only from trusted IP addresses or jump hosts. Additionally, enforcing strong, complex passwords for all administrative accounts reduces the likelihood of credential compromise via brute force or phishing attacks. Regular auditing of device configurations and monitoring for unusual outbound connections can also help detect potential exploitation attempts early in the kill chain.