Anthropic Reviews Reported Access to Restricted AI Model

Anthropic has confirmed that it is investigating a report of unauthorized access to Claude Mythos Preview, a model the company has characterized as too dangerous for public release. The reported access was said to have occurred through a third-party vendor environment.

The company’s statement, reported by Bloomberg and relayed by Gizmodo, said Anthropic had received a report claiming unauthorized access to Claude Mythos Preview through one of its third-party vendor environments. Bloomberg reportedly reviewed a live demo and screenshots from a member of the group said to be responsible for the access.

The facts available publicly are limited, and the report is careful about identifying the people and methods involved. Still, the incident raises a serious governance question for frontier AI labs: even when a model is kept out of public release, vendor access and internal tooling may create paths that are harder to secure than the model itself.

How the Reported Access Happened

According to the source account summarized in the article, the group combined several pieces of information. A Discord group reportedly used bots to search GitHub for information about unreleased AI models. The account also refers to a data breach at the AI training startup Mercor. The group then allegedly combined that information with access available to a person working at an Anthropic contractor.

That chain of events reportedly allowed the group to infer the online location of Claude Mythos. The group is said to have accessed the model since April 7, the same day Anthropic announced Project Glasswing.

The source quoted in the report claimed the group was interested in experimenting with new models rather than causing harm. That claim does not reduce the seriousness of the access issue. If a restricted model is available to an unauthorized party, the risk does not depend only on what the first reported group says it intends to do.