Mythos 5

Mythos 5 is Anthropic’s most capable cybersecurity model, built for high‑stakes penetration testing and large‑scale vulnerability detection. It can scan enormous codebases and identify critical weaknesses in operating systems and browsers. In an authorized exercise disclosed in June 2026, the model breached nearly all classified systems of the US military within hours, demonstrating extreme efficiency.

Its main advantage lies in the breadth and speed of vulnerability discovery. It can replace part of the work of senior security research teams, producing dense vulnerability intelligence that can be used directly to harden critical infrastructure. Within an isolated environment, it can perform defensive assessments and suggest remediation priorities.

The restrictions are severe. It is subject to US export controls and can only be used by US‑based organizations that operate and defend critical infrastructure. Foreign nationals, including Anthropic employees, are excluded. Without built‑in safety classifiers, misuse risk is high, so it is deployed only under strict controls.