This command injection vulnerability in QTS allows attackers to run arbitrary commands in the compromised application. QNAP have already fixed the issue in QTS 4.2.6 build 20170517, QTS 4.3.3.0174 build 20170503 and later versions.
https://www.qnap.com/zh-tw/security-advisory/nas-201707-12
https://www.qnap.com/en/release-notes/qts/4.3.3.0174/20170503