“We’re investigating a report claiming unauthorized access to Claude Mythos Preview through one of our third-party vendor environments,” an Anthropic spokesperson said in a statement to Bloomberg. Anthropic currently has no evidence that the unauthorized access is impacting the company’s systems or goes beyond the third-party vendor’s environment.

The model was reportedly accessed illicitly on April 7th, the same day that Anthropic announced it was releasing Mythos to a limited number of companies for testing. The group that gained the unauthorized access has not been publicly identified, though Bloomberg reports that its members are part of a Discord channel that seeks out information about unreleased AI models.

The group accessed Mythos by using knowledge of Anthropic’s other model formats obtained from a recent Mercor data breach to make “an educated guess” about its online location. Members have been using Mythos regularly since gaining access — providing screenshots and a live demonstration of the model as evidence to Bloomberg — though reportedly not for cybersecurity purposes in an attempt to avoid detection by Anthropic. Other unreleased Anthropic AI models have also been accessed by the group, according to Bloomberg.