Just like Spectre and Meltdown flaw in 2018, the vulnerability was caused by a flaw within an important feature that existed in many modern processors called speculation execution. However, the vulnerability somehow doesn’t impact AMD and ARM processors for the time being. Through this vulnerability, attackers are able to extract sensitive data including browser history, website contents, passwords, and encryption keys. Alongside Intel, major tech companies such as Apple, Google, Microsoft, and Mozilla have begun to work on patches for their products. You are able to check whether your system is affected by it using the MDS Tool that can be downloaded from this site although it is almost certain that you are being hit by it if your system is running on Intel processor. So, always keep your system updated with the latest security patches in order to stay protected from the vulnerability. (Source: Intel // ZombieLoad // MDS Attacks // Wired // TechCrunch.)