OpenAI counters Anthropic's Mythos with Daybreak and three GPT-5.5 cyber models

OpenAI has launched Daybreak, a cybersecurity initiative built around its Codex Security agent and three new GPT-5. OpenAI has launched Daybreak, a cybersecurity initiative built around its Codex Security agent and three new GPT-5.5 variants, including the gated GPT-5.5-Cyber for authorised red teaming. Arriving a month after Anthropic's Project Glasswing and Claude Mythos, Daybreak pitches resilience-by-design over continuous patching. Cloudflare, Cisco, CrowdStrike, Palo Alto Networks, Oracle, Akamai, Zscaler and Fortinet are on board as launch partners.