A Twitter user discovered a backdoor (an exploit) in all OnePlus devices running OxygenOS that could allow anyone to obtain root access to the devices. The application in question is “,” a diagnostic testing application made by Qualcomm for device manufacturers to easily test all hardware components of the device. This APK comes pre-installed on most OnePlus devices, including OnePlus 2, 3, 3T, and the newly-launched OnePlus 5. In response to this issue, OnePlus co-founder Carl Pei said that the company is looking into the matter.
Source: https://thehackernews.com/2017/11/oneplus-root-exploit.html