per the v8 team, efforts to fully secure the JS JIT engine are simply infeasible against some Spectre class attacks: > Fourth, we found that effective mitigati

per the v8 team, efforts to fully secure the JS JIT engine are simply infeasible against some Spectre class attacks: > Fourth, we found that effective mitigation of some variants of Spectre, particularly variant 4, to be simply infeasible in software, even after a heroic effort by our partners at Apple to combat the problem in their JIT compiler.