The analysis says the open-weight frontier trails the closed-weight frontier by roughly six to seven months.
Z.ai's GLM-5.3 is listed as the highest-scoring open-weight model, with a Cyber ECI score of 160.1 and a 90% interval of 155.83 to 166.97. Epoch lists Claude Opus 5.5 at 171.14 and OpenAI's GPT-6 Astra at 171.03 among the current closed-weight leaders. The page classifies GLM-5.3 as restricted-use open weights; the two leading closed models are available by API.
The index is derived from cybersecurity benchmark results and a statistical fit shared with Epoch's broader ECI methodology. It does not establish real-world exploit success rates, deployment safety, or the security consequences of releasing any particular model's weights.