CVE-2026-71904: DrayTek VigorAP Multiple Models OS Command Injection via tr069TestInform

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 eventcode 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.