A private Discord group gained access to Mythos on launch day.
Commentators attribute the breach to a Mercor leak or URL guessing:
- A Discord group member worked for a third-party Anthropic contractor.
- That individual possessed access to Anthropic model-evaluation systems.
- The group scraped clues from GitHub and other sources using OSINT tools.
- The Mercor breach revealed Anthropic’s model naming conventions.
- The group combined the contractor’s access with these conventions to infer the Claude Mythos Preview endpoint.
- The third-party vendor environment authorized the route for the contractor’s account, granting the group access to Mythos.