OpenAI launches Daybreak cybersecurity platform built on Codex and GPT-5.5

Daybreak integrates frontier models and Codex into a four-stage pipeline covering threat modeling, PoC validation, patching, and dependency risk analysis. It's positioned head-to-head against Anthropic's Mythos in the AI-cyber stack and ships across three GPT-5.5 tiers including a red-team-only 'GPT-5.5-Cyber' variant.