Spectre and Meltdown are recently reported security vulnerabilities in most microprocessors. This video explains what Spectre and Meltdown are, which CPUs have these design flaws, and the mitigation measures that may be taken to reduce the security risk.
The TechArp web pages listing all impacted CPUs:
https://www.techarp.com/guides/complete-meltdown-spectre-cpu-list/
The Meltdown Attack website: