Spectre and Meltdown: CPU Design Flaws Expose Private Data Across Process Boundaries
What happened
Researchers disclosed Meltdown and Spectre, fundamental vulnerabilities in the speculative execution designs of virtually all modern CPUs. Meltdown allowed user processes to read kernel memory; Spectre allowed processes to read other processes' memory. Software patches caused performance degradations of up to 30% in I/O-heavy workloads.[1]
What went wrong
CPU manufacturers prioritised performance through speculative execution without adequately modelling the security implications of speculative side effects. The vulnerabilities had been present in hardware for over a decade before disclosure and cannot be fully patched without microcode or hardware redesign.[1]
Lesson learned
Performance optimisations in hardware have security implications that are not visible at the architectural level. The cost of software mitigations (KPTI, retpoline) for hardware design mistakes falls entirely on users — security must be a first-class constraint in CPU design.
Sources
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