Machine Heart

Apr 15, 2026 · Information Security

OpenAI Unveils Cyber‑Focused GPT‑5.4‑Cyber, Sparking Comparison with Anthropic’s Claude Mythos

OpenAI has introduced GPT‑5.4‑Cyber, a security‑tuned version of its GPT‑5.4 model released through the Trusted Access for Cyber (TAC) program, offering higher‑level permissions for vetted defenders and prompting industry observers to compare it with Anthropic’s recently launched Claude Mythos.