In what is termed by many experts as a direct competition to Anthropic’s Mythos, OpenAI launched Daybreak, a cybersecurity initiative designed to help organizations identify and patch vulnerabilities.
The platform uses GPT-5.5 models and Codex Security agent to find software flaws before attackers exploit them. However, Daybreak directly competes with Anthropic’s Project Glasswing which uses Claude Mythos Preview for cyber defense needs.
Anthropic’s Mythos helped Mozilla find and patch 271 vulnerabilities in Firefox during April testing according to reports. OpenAI stated Daybreak is built around integrating cyber defense into software development from the outset. Consequently, the initiative aims to prioritize high-impact issues and reduce analysis time from hours to minutes.
According to OpenAI:
Daybreak combines the intelligence of OpenAI models, the extensibility of Codex as an agentic harness, and our partners across the security flywheel to help make the world safer for everyone. Defenders can bring secure code review, threat modeling, patch validation, dependency risk analysis, detection, and remediation guidance into the everyday development loop so software becomes more resilient from the start.
The initiative uses three model tiers including GPT-5.5 for general purposes and GPT-5.5 with Trusted Access for Cyber. Meanwhile, GPT-5.5-Cyber supports specialized workflows including authorized red teaming and penetration testing under controlled conditions. Major companies like Akamai, Cisco, Cloudflare, CrowdStrike, Fortinet, Oracle, Palo Alto Networks, and Zscaler are already integrating these capabilities.
Access to Daybreak remains tightly controlled with OpenAI urging interested organizations to request vulnerability scans. The company is working with industry and government partners to deploy increasingly cyber-capable models through iterative deployment.
