Intel has released a security advisory about a series of critical vulnerabilities that can lead to loading and executing code even outside the visibility of the operating system.
Intel® Management Engine Critical Firmware Update (Intel SA-00086)
Intel® Product Security Center
Alongside the advisory they have also released a diagnostic tool that allows you to check your system:
Download Intel-SA-00086 Detection Tool
This also comes in a Linux flavor that appears to run in the LibreELEC shell.
So check your systems, ask your manufacturer for BIOS updates if needed, and stay safe.
*A number of Intel NUCs (a favorite for LibreELEC) appear to be vulnerable --> SA-00086 for Intel® NUC, Intel® Compute Stick and Intel® Compute Card
with BIOS updates scheduled for December.