UK AISI finds AI cyber capabilities double every 4.5 months, with Mythos and GPT-5.5 showing token-limited ability, not capability bounds. UK AI Security Institute (AISI) reports AI cyber capabilities double every 4.5 months. Mythos and GPT-5.5 show token-limited ability, not inherent capability constraints. Key facts AI cyber capability doubling time: 4.5 months. Mythos and GPT-5.5 show token-limited ability. No upper bound established for cyber attack effectiveness. Findings from UK state AI Security Institute. Reported via researcher Ethan Mollick on X. The UK's state AI Security Institute (AISI) published findings on the rapid acceleration of AI-driven cyber capabilities. The report, shared via researcher Ethan Mollick [According to @emollick], highlights two key models: Mythos and GPT-5.5. Both models demonstrate significant gains in cyber capabilities, but the critical finding is that establishing an upper bound on their performance is difficult.…