CVE-2026-71906 in VigorAP
Summary
by MITRE • 08/24/2026
Multiple DrayTek VigorAP models contain a command injection vulnerability in the setLan function. The vulnerability is caused by insufficient validation of the lanIp and lanNetmask 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 VigorAP series of wireless access points contains a critical security flaw within its web-based management interface, specifically located in the setLan function responsible for configuring local area network parameters. This vulnerability stems from insufficient input validation and sanitization mechanisms applied to the lanIp and lanNetmask fields before these values are processed by underlying system commands. When an administrator submits configuration changes through the web GUI, the application constructs shell commands using user-supplied data without adequately checking for malicious payloads or special characters that could alter command execution flow. This design oversight allows a remote attacker who has obtained valid administrative credentials to inject arbitrary operating system commands into the device's environment. The severity of this flaw is significantly amplified by the fact that these injected commands are executed with root privileges, granting the attacker complete control over the underlying Linux-based firmware running on the access point.
From an operational perspective, the impact of this vulnerability extends far beyond simple unauthorized configuration changes. An authenticated attacker can leverage command injection to compromise the integrity and availability of the network infrastructure managed by the VigorAP device. By executing arbitrary commands with root-level permissions, an adversary could install persistent backdoors, exfiltrate sensitive network traffic data stored on the device, modify routing tables to facilitate man-in-the-middle attacks, or pivot into other segments of the internal network that rely on this access point for connectivity. The requirement for valid administrative credentials means that this vulnerability is primarily exploitable in scenarios where credential theft has already occurred through phishing, brute-force attacks against weak passwords, or exposure of default credentials due to poor security hygiene by administrators. Consequently, while it does not allow unauthenticated remote code execution, it represents a severe risk when combined with other initial access vectors such as social engineering or network sniffing for password hashes.
This vulnerability aligns closely with Common Weakness Enumeration (CWE) identifier CWE-78, which describes Improper Neutralization of Special Elements used in an OS Command, commonly known as OS Command Injection. The failure to validate and sanitize user input before its use in system calls is a classic example of this weakness category. Furthermore, from the perspective of the MITRE ATT&CK framework, exploitation of this flaw falls under T1059, specifically command and scripting interpretation techniques such as Unix Shell Commands (T1059.004). The attacker utilizes these interpreted commands to achieve lateral movement or persistence within the network environment after gaining initial foothold through compromised credentials. Understanding these mappings helps security teams categorize the risk accurately and align their detection rules with known adversary behaviors associated with command injection attacks on embedded devices.
To mitigate this vulnerability, organizations must prioritize immediate patching of all affected DrayTek VigorAP models to versions that include proper input validation and sanitization in the setLan function. Until patches are applied or deployed, administrators should enforce strict access controls by restricting management interface availability to trusted IP addresses using firewall rules or VLAN segmentation. It is also critical to implement strong password policies to prevent credential theft, which serves as the prerequisite for exploiting this specific command injection flaw. Additionally, deploying network intrusion detection systems that can identify anomalous traffic patterns associated with web-based exploitation attempts may provide an additional layer of defense. Regular audits of administrative access logs should be conducted to detect any unauthorized login attempts or suspicious configuration changes that might indicate ongoing exploitation activities.