Unauthorized group has gained access to Anthropic’s exclusive cyber tool Mythos, report claims

Bloomberg reported that an unidentified online group accessed Anthropic’s Mythos preview through a third-party vendor environment.

The group is said to have used the tool repeatedly, and Anthropic is investigating the claim.

Anthropic says it has not found evidence that its own systems were affected.

The incident raises concerns about vendor risk, model leakage, and misuse of tightly controlled security tools.