There is a CPU vulnerability Microarchitectural Fill Buffer Data Sampling. I use a Linux OS and I think to fix Microarchitectural Fill Buffer Data Sampling you need to update intel microcode or update kernel to a fixed one https://security-tracker.debian.org/tracker/CVE-2018-12130
I updated kernel to a kernel where Microarchitectural Fill Buffer Data Sampling is fixed. After that I run spectre-meltdown-checker and I get STATUS: VULNERABLE to all 4 types of MFBDS. Why ?
CVE-2019-11091 aka 'RIDL, microarchitectural data sampling uncacheable memory (MDSUM)' * Mitigated according to the /sys interface: NO (Vulnerable: Clear CPU buffers attempted, no microcode; SMT disabled) * Kernel supports using MD_CLEAR mitigation: YES (found md_clear implementation evidence in kernel image) * Kernel mitigation is enabled and active: NO * SMT is either mitigated or disabled: YES > STATUS: VULNERABLE (Vulnerable: Clear CPU buffers attempted, no microcode; SMT disabled)