Days after rival Anthropic launched Mythos, OpenAI announces GPT-5.4-Cyber AI model built for cybersecurity defenders

ChatGPT-maker OpenAI has launched GPT-5.4-Cyber, a variant of its flagship model GPT 5.4 launched in March this year. The new GPT-5.4-Cyber is specifically designed for defensive cybersecurity work. Announcing the new model, OpenAI said: “This is a version of GPT‑5.4 which lowers the refusal boundary for legitimate cybersecurity work and enables new capabilities for advanced defensive workflows, including binary reverse engineering capabilities that enable security professionals to analyze compiled software for malware potential, vulnerabilities and security robustness without needing access to its source code”. Notably, the launch comes days after OpenAI-rival Anthropic introduced its frontier AI model Mythos.