A new vulnerability that attacks Direct Memory Access through Thunderbolt or PCI Express ports. These are common on Macs, but also appears on other systems. Multiple OSes are susceptible to this issue.

From the Naked Security Blog:

Nicknamed ‘Thunderclap’ in a presentation at last week’s Network and Distributed System Security Symposium (NDSS), the vulnerability has to do with Direct Memory Access (DMA), a standard technique for speeding up access to main memory from storage, USB controllers, and network and graphics cards.