US official (anonymous) told AP June 24, 2026: Anthropic’s Mythos identified vulnerabilities in classified government systems within hours during Project Glasswing red-team with intelligence agencies. Finding flaws does not mean exploiting them within that timeframe.
Sen. Mark Warner (June 11 hearing): “This tool broke into almost all of our classified systems, not in weeks but in hours” — attributed to NSA/Cyber Command head Gen. Joshua Rudd.
Warner's "broke into" language vs official's "identified vulnerabilities" nuance — discovery ≠ exploitation.
Administration restricted Anthropic Fable 5 and Mythos 5 access citing national security. 10+ cybersecurity experts signed letter: Mythos “quite good” at finding flaws but “not uniquely good.”