In early 2018, cybersecurity researchers discovered two security flaws they said were present in almost every high-end processor made and used by major companies. Known ominously as Spectre and Meltdown, these flaws were troubling because they represented a new type of breach not previously known that could allow hackers to infer secret data—passwords, social security numbers, medical records—from the way computers pre-calculate certain data using architectural features called “out-of-order execution” and “speculative execution” to speed up their processes.