Hardware backdoors in some x86 CPUs

Security researchers have discovered a hardware backdoor in some VIA C3 x86 processors that allows unprivileged code to bypass kernel protections and access sensitive kernel data. The backdoor consists of a non-x86 embedded core that is normally disabled but has been found enabled by default on some systems, enabling any user-level code to modify kernel memory. This vulnerability is limited to older VIA C3 processors used in industrial, consumer, and embedded systems, and the research has been released as a case study on identifying potential hardware backdoors.