Google has released the Chrome OS 75 update that includes new mitigations for the Microarchitectural Data Sampling (MDS) speculative execution vulnerabilities disclosed in May. In May 2019, a new class of speculative execution attacks were disclosed called RIDL, Fallout, and ZombieLoad that could allow malicious programs to steal sensitive data from memory locations they would normally not have access. In order to eliminate these vulnerabilities, Chrome OS 74 completely disabled hyper-threading by default. The new version of Chrome OS also includes the following new features.
Source: https://www.bleepingcomputer.com/news/google/google-chrome-os-75-released-with-zombieload-mds-mitigations/