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Anthropic's Mythos AI Cracks NSA Classified Systems, Prompting US-Ordered Global Shutdown

Published
Score
10

Why it matters

On June 11, General Joshua Rudd, head of the NSA and US Cyber Command, told the Senate Intelligence Committee that Anthropic's Mythos AI had breached nearly all classified US government systems within hours during a sanctioned cybersecurity evaluation. The following day, the Trump administration ordered Anthropic to restrict access to its Fable 5 and Mythos 5 models to US citizens only. Unable to verify nationality at scale, Anthropic shut down both models globally within 90 minutes, severing access for allied governments, researchers, and foreign-national employees.

Mythos identified thousands of zero-day vulnerabilities across major operating systems and browsers, including flaws in OpenBSD and FFmpeg that had gone unpatched for 27 and 16 years respectively. The UK AI Safety Institute confirmed the model can autonomously target poorly defended enterprise systems, with ArmorCode analysis showing working exploits were generated in over 83 percent of cases. The immediate trigger for the ban was discovery of a jailbreak method that could circumvent Fable 5's safety classifiers and unlock sensitive cybersecurity capabilities.

This marks the first time the US government has applied export controls to an AI model based on emergent capabilities rather than intentional design. Attorneys should monitor how this precedent reshapes AI governance and export policy, particularly as other advanced models develop unintended capabilities. The incident also signals heightened scrutiny of AI safety measures and potential liability exposure for developers whose systems identify but do not disclose critical vulnerabilities. Anthropic has since formed Project Glasswing with Apple, Google, NVIDIA, and JPMorgan Chase to use Mythos defensively, identifying over 10,000 critical vulnerabilities in their codebases.

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