On May 14, 2019, Intel and other industry partners shared more details and mitigation information about a group of vulnerabilities collectively called Microarchitectural Data Sampling (MDS).
MDS is a subclass of previously disclosed speculative execution side channel vulnerabilities. It was first identified by Intel's internal researchers and partners, and then independently reported by external researchers.
Please go to Intel's Security First website for the full details.
A list of impacted products can be found here.