Spectre is a vulnerability that affects modern microprocessors that perform branch prediction. On most processors, the speculative execution resulting from a branch mis-prediction may leave observable side effects that may reveal private data to attackers.

Spectre is a hardware design flaw in the architectures of Intel, AMD, and ARM processors that allows code running inside a malicious application to break the isolation between different applications at the CPU level and then steal sensitive data from other apps running on the same system.