Claude Mythos 5.1 built working exploits in 245/250 Firefox trials with safeguards off
rohanpaul_ai · x · 2026-09-02
With safeguards switched off, Claude Mythos 5.1 produced fully working exploits in 245 of 250 Firefox trials — a 98% success rate, up from 52% for the previous flagship six months ago. The striking part: the model's bug-finding ability barely changed; what jumped is its ability to weaponize a handed-to-it bug.
The same thread notes Fable 5.1's cache reads cost 75% less than Fable 5's. Since agents constantly revisit context and tool outputs, that single-component cut compounds to 45% off entire agentic workloads — reframing enterprise economics as "how long can an agent keep working before the job stops making financial sense?"
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