Seven new Meltdown and Spectre attacks affecting AMD, ARM, and Intel CPUs were revealed by researchers this week. These include Meltdown-BR, which exploits an x86 bound instruction on Intel and AMD processors, and Meltdown-PK, which bypasses memory protection keys on Intel CPUs. ARM and Intel have already acknowledged the researchers' findings.
Researchers say they've discovered the seven new CPU attacks while performing "a sound and extensible systematization of transient execution attacks" -- a catch-all term the research team used to describe attacks on the various internal mechanisms that a CPU uses to process data, such as the speculative execution process, the CPU's internal caches, and other internal execution stages.
The research team says they've successfully demonstrated all seven attacks with proof-of-concept code. Experiments to confirm six other Meltdown-attacks did not succeed, according to a graph published by researchers.