The UK's AI Safety Institute (AISI) found that GPT-5.5 completed a multi-step corporate network attack simulation in 11 minutes at $1.73 — a task estimated to take a human expert 12 hours. It is the second model after Anthropic's Claude Mythos to reach this benchmark, confirming that advanced AI cyber capabilities are an industry-wide trend.
The Reddit thread did not stop at “GPT-5.5 is strong.” Its headline mixed together two different official results, and commenters immediately locked onto the harder question: how cheap and repeatable frontier-model cyber capability is becoming.
A Reddit thread pulled attention to AISI’s latest Mythos Preview evaluation, which shows a step change not just on expert CTFs but on multi-stage cyber ranges. The important claim is not generic danger rhetoric, but that Mythos became the first model to complete a 32-step corporate attack simulation end to end.