Data-sampling attacks are different from and more dangerous than Meltdown, Spectre and their variations because they can leak data from CPU buffers, which is not necessarily present in caches. Meltdown and Spectre are the first of this type of attacks, disclosed in January 2018. RIDL, Fallout, and ZombieLoad attacks exploit a set of four vulnerabilities collectively named as Microarchitectural Data Sampling (MDS) vulnerabilities. The flaws affect Intel CPUs released since 2008, the researchers say.
Source: https://www.bleepingcomputer.com/news/security/new-ridl-and-fallout-attacks-impact-all-modern-intel-cpus/