Researchers from Microsoft and Google have discovered a fourth variant of the data-leaking Meltdown-Spectre security flaws. Variant 4 takes advantage of speculative execution that modern CPUs use to potentially expose sensitive data through a side channel. If enabled, Intel observed a performance hit of approximately 2 to 8 percent on overall scores for benchmarks like “SYSmark 2014 SE and SPEC integer rate on client and server test systems” Variant 4 affects modern processor cores from Intel, AMD, and ARM, as well as IBM’s Power 8, Power 9, and System z CPUs.
Source: https://thehackernews.com/2018/05/fourth-critical-spectre-cpu-flaw.html