CVE-2026-71904 in VigorAP
Summary
by MITRE • 08/24/2026
Multiple DrayTek VigorAP models contain a command injection vulnerability in the tr069TestInform function. The vulnerability is caused by insufficient filtering of dangerous characters before the event_code field is concatenated into a system 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 identified security flaw resides within the tr069TestInform function of multiple DrayTek VigorAP wireless access point models, representing a critical command injection vulnerability that stems from inadequate input validation mechanisms. The core technical deficiency lies in the application's failure to properly sanitize or filter dangerous characters before concatenating user-supplied data into system-level commands. Specifically, when processing the event_code field, the software directly incorporates this variable into an operating system shell execution context without implementing necessary escape sequences or whitelist-based filtering for special symbols such as semicolons, pipes, ampersands, and backticks. This architectural oversight allows a malicious actor to inject arbitrary command strings that are subsequently interpreted by the underlying OS shell rather than being treated strictly as data parameters.
From an operational perspective, this vulnerability enables remote code execution with root privileges, which constitutes the highest level of system access available on most embedded Linux-based networking devices. Although exploitation requires valid administrative credentials for the device's web management interface, the presence of such a flaw significantly lowers the barrier to entry for attackers who have obtained or guessed these credentials through phishing, brute force attacks, or credential stuffing campaigns. Once authenticated, an attacker can manipulate the event_code parameter to execute arbitrary system commands, effectively gaining full control over the network infrastructure managed by the affected VigorAP devices. This level of access allows for comprehensive surveillance, traffic interception, configuration tampering, and potentially using the compromised device as a pivot point for lateral movement within the internal network.
The technical classification of this vulnerability aligns with CWE-78 Improper Neutralization of Special Elements used in an OS Command, commonly referred to as command injection. The attack vector is categorized under ATT&CK technique T1059 Command and Scripting Interpreter, specifically involving indirect execution through system utilities. Furthermore, the requirement for authentication places this within the context of authenticated remote exploitation, which often falls under privilege escalation scenarios if the initial access was gained via lower-privileged accounts or credential reuse across services. The impact extends beyond simple device compromise to include potential denial of service conditions if malicious commands disrupt network connectivity or firmware integrity checks.
Mitigation strategies must prioritize immediate patching by applying vendor-provided firmware updates that address this specific input validation gap in the tr069TestInform function. In scenarios where updating is not immediately feasible, administrators should enforce strict access control policies to limit exposure of the web management interface, ideally restricting it to trusted IP addresses or virtual private networks rather than exposing it directly to untrusted networks. Additionally, implementing network segmentation can isolate critical infrastructure from general user traffic, reducing the blast radius in case a device is compromised. Regular auditing of administrative credentials and enforcing multi-factor authentication where supported further reduces the likelihood of credential-based exploitation that precedes this command injection attack vector.