GPT-5.4 Thinking System Card
Hacker News
March 5, 2026
GPT‑5.4 Thinking is the latest reasoning model in the GPT‑5 series, and explained in our blog. The comprehensive safety mitigation approach for this model is similar to previous models in this series, but 5.4 Thinking is the first general purpose model to have implemented mitigations for High capability in Cybersecurity. The approach to cyber safety builds on the latest approaches implemented for GPT‑5.3 Codex, in ChatGPT and the API.
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Originally published on Hacker News on 3/5/2026