Spectre is one in a list of critical vulnerabilities in modern processors that was discovered over the last few years, and it seems it's not been solved yet. Despite new hardware designs, and updates to the Linux Kernel and more to defend against the issues, researchers at University of Virginia School of Engineering claim to have a new discovery that could have a huge impact.
Affecting both AMD and Intel, in a post titled "Defenseless", UVA Engineering say we will "have to go back to the drawing board" when it comes to defending against it as they've "uncovered a line of attack that breaks all Spectre defenses, meaning that billions of computers and other devices across the globe are just as vulnerable today as they were when Spectre was first announced".
What they're doing is exploiting a "micro-op cache" that "speeds up computing by storing simple commands and allowing the processor to fetch them quickly and early in the speculative execution process". What they found is that they can pinch data from it when a processor tries fetching from this cache. Current defenses for Spectre deal with what happens later on for speculative execution and so they don't help here.
Their team disclosed the vulnerabilities to AMD and Intel already, and they gave a tech talk at Intel Labs worldwide April 27, to talk about potential fixes.