Computer security is hard – even when there is hardware dedicated for the purpose.
Overclocking has been an interesting field for computer design and providing really interesting knobs to tune performance. This is done by pushing a CPU, memory, and other components past their normal voltage and frequency limits by adding cooling solutions or exploiting engineering headroom limits.
Undervolting is the opposite. It lowers power and/or frequency. This can be used constructively to save power on your laptop if it isn’t doing anything. But if you starve it enough, you end up with memory corruption and crashes. When done in certain ways, you can cause faults and corruption without crashing the CPU – leaking secrets.
Plundervolt is one such exploit. Give it a watch.