GPT-5.3-Codex System Card

OpenAI released the GPT-5.3-Codex system card, calling it its strongest agentic coding model yet.

The model is described as better at long-running tasks and interactive collaboration, with gains over GPT-5.2-Codex and GPT-5.2.

OpenAI said it is treating the model as high capability for biology and, for the first time, high capability for cybersecurity.

That classification triggers additional safeguards under the Preparedness Framework, adding stricter risk controls as the model is deployed.