According to researchers, Spectre breaks the isolation between different applications and allows an attacker to trick error-free programs, which follow best practices, into leaking their secrets. Per researchers, the very same safety checks of said best practices actually increase the attack surface and may make applications more susceptible to Spectre.

While the Meltdown attack impacted only Intel CPUs, Spectre was an industry-wide problem, also impacting AMD and ARM processors as well.

Just like Meltdown, Spectre is the result of performance-driven design. The vulnerability leaks data from a CPU's "speculative execution," a series of operations that CPUs calculate in advance to guess a possible outcome and cut down future computing time.