Anthropic’s Unreleased Claude Mythos Might Be The Most Advanced AI Model Yet
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Anthropic is testing an unreleased artificial intelligence (AI) model with capabilities that exceed any system it has previously released, and an
Anthropic’s Unreleased Claude Mythos Might Be The Most Advanced AI Model Yet By PYMNTS | March 31, 2026 | Anthropic is testing an unreleased artificial intelligence (AI) model with capabilities that exceed any system it has previously released, and an accidental data leak forced the company to confirm what it had not yet announced. Get the Full Story Complete the form to unlock this article and enjoy unlimited free access to all PYMNTS content — no additional logins required. yesSubscribe to our daily newsletter, PYMNTS Today. By completing this form, you agree to receive marketing communications from PYMNTS and to the sharing of your information with our sponsor, if applicable, in accordance with our Privacy Policy and Terms and Conditions. Δ According to a Thursday (March 26) report by Fortune, a configuration error in Anthropic’s content management system left nearly 3,000 unpublished documents in a publicly searchable data store, including a draft blog post describing the model as “by far the most powerful AI model we’ve ever developed.” Independent security researchers at LayerX Security and the University of Cambridge found the materials before Anthropic restricted access. An Anthropic spokesperson confirmed the model’s existence to Fortune, calling it a step change and the most capable system the company has built, with meaningful advances in reasoning, coding and cybersecurity. The company said it is testing the model, known as Claude Mythos, with a small group...
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