V8: A Year with Spectre

Using the speculative execution mechanisms of CPUs, an attacker could temporarily bypass both implicit and explicit safety checks in code that prevent programs from reading unauthorized data in memory. Such timers are precise enough to detect individual L1 cache hits and misses, which is usually how Spectre gadgets leak information. In V8 we face many other security threats that are much worse, from direct out-of-bound reads due to regular bugs (faster and more direct than Spectre), out-of-bound writes (impossible with Spectre, and worse) and potential remote code execution (impossible with Spectre and much, much worse).

Source: v8.dev