# A small group accessed Claude Mythos Preview by guessing the model’s URL on the same day Anthropic announced Project Glasswing.

*genai · news · 2026-04-22 · TNW*

## Key points

- Unauthorized users accessed Anthropic's restricted Claude Mythos Preview by guessing its URL format.
- A third-party contractor working with Anthropic is implicated in facilitating the unauthorized group's access.
- Mythos Preview autonomously found thousands of zero-day vulnerabilities and composed advanced working exploits.
- The breach exploited weaker controls at a vendor environment, not Anthropic’s core systems directly.
- This incident undermines Anthropic’s claims of rigorous access controls during ongoing legal disputes with the government.

**Companies:** Amazon Web Services, Apple, Google, Microsoft, Nvidia, Broadcom, Cisco, CrowdStrike, JPMorganChase, Palo Alto Networks
**Countries:** United States

[Read the full story on TNW](https://thenextweb.com/news/anthropic-mythos-unauthorized-access-vendor-breach)

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