GPT-5.5 completed a 12-hour expert cyberattack simulation in just 11 minutes. OpenAI followed by launching GPT-5.5-Cyber, a purpose-built security model for critical infrastructure defenders.
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.
Sam Altman announced the rollout of GPT-5.5-Cyber, a frontier AI model purpose-built for cybersecurity. Initial access is limited to critical cyber defenders, with broader access to follow as trusted frameworks are established.