# GPT-5.3-Codex

- [GPT-5.3-Codex: The First AI Model That Helped Build Itself — and Got a Scary Security Rating](https://sdd.sh/2026/03/gpt-5.3-codex-the-first-ai-model-that-helped-build-itself-and-got-a-scary-security-rating.md): OpenAI's GPT-5.3-Codex was instrumental in creating itself, introduced mid-turn steering for agentic workflows, and became the first OpenAI model rated 'High capability' for cybersecurity — which means it can reliably exploit real vulnerabilities.