Project
SpiderMonkey is Mozilla's JavaScript and WebAssembly engine, used in Firefox to execute web scripts via interpretation and JIT compilation.
VUSec disclosed Branch Target Reuse, a Spectre-v2 attack on JIT engines whose Linux exploit leaks memory at 8 bytes a second. It bypassed every enabled mitigation, and the kernel's fix had already shipped in July.
Reality
Intel, AMD and Arm say their IBPB barrier can block Branch Target Reuse, a Spectre v2 variant hitting all three, if JIT software calls it. Each kernel, browser and runtime that rewrites JIT code now has to add that call itself.
Perspective Coverage
3 publishersReality
Anthropic's red team says the scarce reverse-engineering skill that used to give defenders weeks is no longer the bottleneck. It measured that on Firefox and Windows kernel fixes, where a 19-day median gap counts as fast.
Reality
Anthropic sent 8% of its model's 23,019 findings out for review and stopped there, citing a shortage of people to check them. Where independent scoring did happen, 14 of 27 severity ratings had to be moved.
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At one million points the Rust build tied its JavaScript fallback, so the author went looking for the measurement behind "WASM adds another 5-10x on top" before shipping, and found there was none.
Reality