Anthropic Mythos AI Leak Triggers Access Restrictions

The announcement follows a data leak by the San Francisco start-up last month, when descriptions of the Mythos model and other documents were discovered in a publicly accessible data cache. Last week, Anthropic suffered a second incident, leading to the internal source code for its personal assistant, Claude Code, being made public. The cases caused concerns over Anthropic's data vulnerabilities and security practices.

In both instances, the company said "human error" was responsible for the data being made public. Mythos has been in use with partners for several weeks. Although it is a "general purpose" model with wider capabilities, it is the first time the company has limited release of a model due to its capabilities in cyber security.

Anthropic said the software can identify cyber vulnerabilities at a scale beyond human capacity, but it could also develop ways to exploit these vulnerabilities, which bad actors could use. The company said the model could "reshape" cyber security practices and does not plan a broad release. "We believe technologies like this are powerful enough to do a lot of really beneficial good but also potentially bad if they land in the wrong hands," said Dianne Na Penn, head of product management, research at Anthropic, adding selected companies would "get a head start on being able to secure vulnerabilities and detect code at a scale they couldn't have done before."