In mid-2020, DARPA created a bug bounty program dubbed Finding Exploits to Thwart Tampering (FETT), to which it invited more than 500 cybersecurity experts tasked to breach certain experimental computer processors. Morpheus, the "unhackable" processor developed by the University of Michigan was the only one to live up to its nickname.
https://www.notebookcheck.net/World-s-best-500-cybersecurity-experts-fail-to-hack-the-Morpheus-processor.526402.0.html