security in computers is hard. if we keep introducing security problems already in hardware, there is no need to discuss any software related issues anymore.
any intel cpu newer than (including) 9th generation are affected and the bug has been shown to work as far back as 7th generation by researchers at eth zurich. this specific vulnerability could be used on already breached machines for privilege escalation attacks.
for mitigation, intel provides microcode updates with some drawbacks to performance. keep an eye out for the microcode updates on affected machines.