Anthropic's Mythos Preview solves previously unsolvable cybersecurity test in updated checkpoint
A month after its initial release, a newer checkpoint of Anthropic's Mythos Preview became the first model to complete the UK AI Safety Institute's 'Cooling Tower' cyber range, solving it in 3 of 10 attempts. The model also completed 'The Last Ones' range in 6 of 10 attempts, surpassing OpenAI's GPT-5.5 and demonstrating capability improvements within a single model version.