CVE-2026-71913 in VigorAP
Summary
by MITRE • 08/24/2026
Multiple DrayTek VigorAP models contain a command injection vulnerability in the upload_settings.cgi interface. The vulnerability is caused by insufficient filtering before the restorekey field is concatenated into a shell command. 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 VigorAP series of wireless access points contains a critical security flaw within its web-based management interface, specifically located in the upload_settings.cgi script responsible for handling configuration restoration operations. This vulnerability stems from an improper neutralization of special elements used in shell commands, commonly categorized under CWE-78 as OS Command Injection. The root cause lies in the application's failure to adequately sanitize or validate user-supplied input before it is processed by the underlying operating system. Specifically, when a user initiates a configuration restore process, the value provided for the restorekey field is directly concatenated into a shell command string without sufficient filtering of metacharacters such as semicolons, ampersands, or pipe symbols. This architectural oversight allows an attacker to inject arbitrary commands that are executed by the system with elevated privileges.
From an operational perspective, this vulnerability represents a significant risk vector for network administrators and organizations relying on DrayTek infrastructure for secure wireless connectivity. Although exploitation requires valid administrative credentials for the device's web management interface, which implies some level of initial access or credential compromise, the impact is severe due to the privilege level at which commands are executed. An authenticated attacker can leverage this flaw to execute arbitrary system commands with root privileges on the affected VigorAP devices. This capability effectively grants full control over the network appliance, allowing for complete bypass of security controls, installation of persistent backdoors, or use of the device as a pivot point for further lateral movement within the internal network. The ability to run commands as root means that standard access restrictions are rendered ineffective once this injection is successful.
The exploitation technique aligns with ATT&CK tactic T1059, specifically sub-technique T1059.004 which covers Command and Scripting Interpretation, where attackers use system utilities like sh or bash to execute malicious payloads. The attack vector involves crafting a specific HTTP request that targets the upload_settings.cgi endpoint, embedding shell metacharacters within the restorekey parameter to break out of the intended command context. This allows the injection of additional commands that are then interpreted and executed by the operating system's command interpreter. Given that many enterprise environments may have administrative credentials exposed through phishing or weak password policies, this vulnerability significantly lowers the barrier for an attacker to achieve remote code execution on critical network infrastructure components.
Mitigation strategies must focus on both immediate remediation and long-term hardening of the management interface. The primary defense is to apply the vendor-provided firmware update that addresses this input validation flaw by properly escaping or rejecting special characters in the restorekey field before command construction. Until patches are applied, administrators should restrict access to the web management interface using network segmentation policies, ensuring it is only accessible from trusted administrative subnets rather than exposed directly to untrusted networks like the internet. Additionally, enforcing strong, complex passwords for all administrative accounts and enabling multi-factor authentication where supported can reduce the likelihood of credential compromise that precedes exploitation. Regular auditing of configuration changes and monitoring for unusual outbound traffic from managed devices can also aid in early detection of potential abuse attempts leveraging this vulnerability.