So this one is significant given that all modern systems employ power management software and firmware to one degree or another. It’s not trivial to exploit but it is something that could be done remotely, thus increasing the possibility of someone doing it by orders of magnitude.
A new vulnerability in Intel and AMD CPUs lets hackers steal encryption keys | Ars Technica
BTW: The article doesn’t go in to it, but the researcher that initially discovered it did so somewhat by accident, examining one of the easily available battery manager apps that have proliferated out there.