If the reports are accurate, it appears that Intel might have a pretty severe chip-level security bug on its hands that cannot be simply swatted away with a microcode update. The bug affects all modern Intel processors dating back at least a decade.
We should note that squashing the bug requires a patch at the OS level; and Linux patches

Source: Hot Hardware – Huge Intel CPU Bug Allegedly Causes Kernel Memory Leak With Up To 30% Performance Hit