https://www.theregister.co.uk/2018/05/21/spectre_meltdown_v4_microsoft_google/

Breaking Today, Microsoft and Google Project Zero will reveal a fourth variant of the speculative-execution-based security vulnerabilities in modern processors – the design flaws known as Spectre and Meltdown.

These holes can be exploited by malicious software running on a vulnerable computer, or a miscreant logged into the system, to potentially extract secrets, such as passwords, from protected kernel or application memory, depending on the circumstances.