Open cyber models still trail the closed frontier by 6 to 7 months
Open-weight models now reach the cybersecurity capability level of closed models from roughly 6 to 7 months earlier, so their misuse risk should not be judged against today’s closed frontier alone. Epoch’s Cyber ECI, a cybersecurity-focused capability score, puts Z.ai’s GLM-5.3 at 160, ahead of OpenAI’s GPT-5.4 from March 2026. It still trails Claude Mythos Preview and GPT-5.5, both released in April 2026.