4 min readNew DelhiUpdated: Apr 23, 2026 09:02 AM IST
Anthropic has reportedly swung into action after a report claimed unauthorised users gained access to its unreleased Claude Mythos model. Earlier this month, while announcing its latest AI model, the company had said it is limiting access to the model over concerns that it could be misused by hackers. However, the latest development seems to have triggered a fresh bout of concerns around access controls and overall AI safety.
On Wednesday, April 22, Bloomberg reported that a small group of people accessed the model through one of Anthropic’s third-party vendor environments. Following the report, the US-based AI startup released a statement indicating that it has begun investigating the matter. In its report, the publication had revealed that a handful of users in a private online platform gained access to Claude Mythos the day when Anthropic announced that it was releasing the model to a small set of companies, including Goldman Sachs and Apple, for testing.
One of the unidentified users, who was a worker at a third-party contractor for Anthropic, reportedly accessed the advanced AI model. The Bloomberg report said that the users did not run any cybersecurity prompts on the model but were more interested in simply playing around with the technology. This was verified by the publication based on screenshots and a live demo of the model. Regardless, the possibility of a potential breach of Claude Mythos has raised widespread security concerns.
What is Mythos?
Mythos is a large language model (LLM) that is said to be capable of a wide range of tasks, including the ability to identify zero-day vulnerabilities in software systems. The model reportedly builds on the recent trend of LLMs advancing their performance on code-related tasks. Its system allows Mythos to instantly find and patch software vulnerabilities. It is backed by considerable compute power and is reportedly trained on troves of software-relevant data.
Upon its announcement, Anthropic had shared that access to Mythos would be limited to a closed group of collaborators across the tech and security ecosystem. According to the company, the objective behind Mythos is to strengthen defensive cybersecurity capabilities at a time when the world is witnessing sophisticated AI-driven cyber threats. Claude Mythos not only identifies vulnerabilities but can also assist in understanding how they would be exploited. In essence, Mythos comes with defensive benefits as well as serious potential risks. The model is part of Anthropic’s Project Glasswing, for which the company has pledged up to $100 million in usage credits and $4 billion toward open-source security efforts.
According to a report in The Guardian, the model has drawn scrutiny from one of the world’s leading safety authorities for technology – the UK’s AI Security Institute, which had cautioned last week that Mythos was a step up from earlier models when it came to the cyber-threats it posed. The Institute claimed that the AI model could orchestrate attacks that would require multiple actions and could even detect weaknesses in IT systems without any human intervention. Mythos was reportedly the first AI model to complete a 32-step simulation of a cyber-attack created by the institute. In these steps, the model was required to solve the challenge in three out of 10 trials.
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