Attack Chain

1. Attacker gains administrative access to the VigorSwitch web management interface through compromised credentials or brute force.
2. Attacker navigates to the configuration or diagnostic page that utilizes the commandTable function.
3. Attacker intercepts or crafts an HTTP POST request targeting the parameter field associated with the commandTable functionality.
4. Attacker embeds shell metacharacters (e.g., backticks, semicolons, or newlines) and malicious commands into the parameter input.
5. The web application fails to sanitize the input, passing the malicious payload directly to the underlying system shell.
6. The switch executes the injected command with the privileges of the web management service (root).
7. Attacker establishes persistence, exfiltrates sensitive network configuration data, or pivots deeper into the internal network.

Impact

Successful exploitation of CVE-2026-71916 allows an authenticated attacker to execute arbitrary commands with root privileges on the targeted DrayTek VigorSwitch. This can lead to full device control, interception of network traffic, modification of switch configurations, and potential lateral movement into the local network segment. Organizations relying on these switches for critical network infrastructure are at risk of complete traffic inspection and disruption if administrative credentials are compromised.

Recommendation

• Apply the latest firmware patches provided by DrayTek to address CVE-2026-71916.
• Restrict access to the VigorSwitch web management interface to trusted management subnets or IP addresses only.
• Implement multi-factor authentication (MFA) for all administrative accounts if supported, and mandate strong, unique passwords to prevent unauthorized access to the management console.
• Monitor webserver logs or network traffic for anomalous HTTP POST requests containing shell metacharacters directed at switch management endpoints.