Anthropic’s ‘Most Capable’ AI Model Claude Mythos Leaks, Deemed Major Cybersecurity Threat

Claude creator Anthropic is growing a brand new AI mannequin known as Claude Mythos, described internally as the corporate’s most succesful mannequin thus far, with draft supplies in regards to the system being leaked on-line this week.

The existence of the mannequin was first reported by Fortune on Thursday after unpublished recordsdata tied to Anthropic’s weblog have been found in a publicly accessible information cache. An Anthropic spokesperson confirmed the existence of the mannequin to the publication.

“We’re growing a basic goal mannequin with significant advances in reasoning, coding, and cybersecurity,” an Anthropic spokesperson informed Fortune. “Given the power of its capabilities, we’re being deliberate about how we launch it. As is commonplace observe throughout the business, we’re working with a small group of early entry prospects to check the mannequin. We take into account this mannequin a step change and essentially the most succesful we’ve constructed thus far.”

In an archived growth web page reviewed by Decrypt, Anthropic known as Mythos “essentially the most highly effective AI mannequin we’ve ever developed.”



“Mythos is a brand new identify for a brand new tier of mannequin: bigger and extra clever than our Opus fashions—which have been, till now, our strongest,” Anthropic wrote. “We selected the identify to evoke the deep connective tissues that hyperlink collectively data and concepts.”

In accordance with Anthropic, Mythos scored “dramatically greater” than Claude Opus 4.6 on checks of software program coding, tutorial reasoning, and cybersecurity.

The leak of Mythos seems to have originated from draft supplies saved in an unsecured content material administration system. In accordance with Fortune, Anthropic restricted public entry to the info retailer after being notified that the recordsdata have been searchable on-line. The corporate attributed the publicity to human error within the configuration of its CMS instruments.

Nevertheless, Anthropic’s paperwork labeled Mythos as model one of many new mannequin, and described model two internally as “Capybara,” which the corporate additionally positioned above its present top-tier Opus fashions.

The draft supplies additionally highlighted considerations in regards to the system’s potential cybersecurity implications.

“Though Mythos is at present far forward of every other AI mannequin in cyber capabilities, it presages an upcoming wave of fashions that may exploit vulnerabilities in ways in which far outpace the efforts of defenders,” the corporate wrote.

Due to these dangers, the corporate stated it plans to launch the mannequin cautiously, starting with a restricted early-access rollout geared toward organizations engaged on cybersecurity protection.

Anthropic didn’t instantly reply to Decrypt’s request for remark.

Whereas Anthropic took down the weblog publish, information of the leak rapidly spilled into monetary markets.

Shares of a number of cybersecurity corporations dropped after the stories surfaced, together with Palo Alto Networks (PANW), which fell about 7%, and CrowdStrike (CRWD), which dropped roughly 6.4%. In the meantime, Zscaler (ZS) declined round 5.8%, and Fortinet (FTNT) slipped about 4% throughout Friday buying and selling, in keeping with Yahoo Finance.

The selloff response echoes an identical market response to the reveal of a brand new Anthropic product. In February, Anthropic unveiled Claude Cowork, an AI system designed to automate complicated office duties—together with contract evaluation and compliance—which triggered a broad sell-off throughout software program and professional-services corporations.

That sell-off erased roughly $285 billion in market worth as buyers reassessed the long-term impression of AI brokers on enterprise software program companies.

“The market’s response was a sign, not that AI brokers will instantly change these companies, however that buyers are lastly pricing within the structural danger that basis mannequin suppliers can now compete instantly with the software program layer,” Nexatech Ventures founder Scott Dylan informed Decrypt on the time. “That is a well mannered manner of claiming if Anthropic can construct a authorized workflow device in-house, what’s stopping them from doing the identical for finance, procurement, or HR?”