That sounds like it's leaking across user/process boundaries on a single EC2 instance, which presumably also requires the processes to be running on the same co

That sounds like it's leaking across user/process boundaries on a single EC2 instance, which presumably also requires the processes to be running on the same core. Leaks between different EC2 instances would be far more serious, but I suppose that wouldn't happen unless two tenants / EC2 instances shared SMT cores, or the contents of the microarchitectural register file was persisted across VM context switches in an exploitable manner.