These days, the market is flooded with AI models to use. You’ve got GPT, Gemini, Llama, Mistral, and of course, the ever-popular Claude. Now, Anthopic offers a model to help with cybersecurity-related tasks as well called Claude Mythos. And like with any model, there are important things you should know about it, such as capabilities, pricing, and limitations.

In this article, I’m going to demystify what Claude Mythos is and how it matches up against similar industry models, including its strengths and limitations. 

What is Claude Mythos?

Claude Mythos, developed by Anthropic, is a large language model (LLM). While it was trained to be a general-purpose model, it is particularly useful in completing cybersecurity-related tasks that involve multiple steps. It is also useful for assisting in software engineering, long-running agentic workflows, and industry research.

Currently, Claude Mythos Preview (the current version of the model) is only available as a gated research preview called “Project Glasswing,” and not to the general public.

What is Project Glasswing?

Project Glasswing is the term for Anthropic’s initiative to release Claude Mythos Preview to a limited group of “critical industry partners and open source developers” under terms that “restrict its uses to cybersecurity.” 

Anthropic states this is because it is “concerned” about Mythos’s cybersecurity skills being too powerful and the risk of it being misused by bad actors, particularly for conducting complex, multistage cyber attacks and detecting vulnerabilities in important software applications.

How does Claude Mythos compare to other models?

Claude Mythos Preview does seem to be notably better at completing certain cybersecurity-related tasks, but preliminary research suggests that Anthropic may be overselling its abilities. 

The UK Government’s AI Security Institute (AISI) recently published an initial evaluation of Claude Mythos Preview . It found that while Mythos was not significantly better at individual cybersecurity tasks compared to other models, it did complete difficult multistep infiltration challenges with a high level of frequency, including some that no other AI had completed to date.

When it came to expert-level Capture the Flag tasks (CTF), AISI found Mythos Preview succeeded 73% of the time, shown below. 

AISI’s ultimate conclusion was that Mythos would be good at exploiting systems with “poorly defended systems” and that real-world systems, unlike the testing conditions, had active defenders and defensive tooling that would make success far more difficult.

Meanwhile, many cybersecurity experts have been quick to question if Anthropic’s “concern” around releasing Claude Mythos was just an elaborate sales pitch. Notably, renowned security researcher Bruce Schneier said Anthropic was “convincing a lot of people that Mythos is this amazing step change in capability when the evidence right now… is that it might not be.”

Ironically, word of Claude Mythos first came out in March when Anthropic accidentally left a draft blog post about it in an unsecured, publicly available data cache, which described it as “far ahead of any other AI model in cyber capabilities" and warned it could spark a wave of advanced attacks.” Immediately after, cybersecurity stocks cratered.

Unfortunately, because Mythos isn’t in the wild yet, it’s not on things like LMSYS’s chatbot arena leaderboard, which would allow some crowd-sourced ranking of the model (although given the open-ended nature of the tasks they complete, the best test is often just trying out the model for yourself.)

What is Claude Mythos’s context window and output?

Claude Mythos Preview has a context window of 1M tokens and a max output of 128K tokens.

What is Claude Mythos’s knowledge cutoff date?

Claude Mythos preview has a knowledge cutoff date of December 2025.

How do I get access to Claude Mythos?

It’s one of those cases of “Don’t call us, we’ll call you.” You can access Claude Mythos Preview as a gated preview through Amazon Bedrock in the US East (N. Virginia Region), but it’s limited to an initial allow-list of organization. According to AWS, “If your organization has been allow-listed, your AWS account team will reach out directly.”

How much does Claude Mythos cost?

Other than a vague statement on Anthropic’s website that Claude Mythos Preview will include the full 1M token context window at standard pricing, there’s no information as of yet on base token cost or similar information.

Conclusion

Right now, the industry is waiting to see how substantiated Anthropic’s claims about Claude Mythos really are. Given the wild popularity of Claude Code in software development circles, and the domination of Claude on LLM leaderboards, there’s a mix of skepticism and anticipation right now. 

This article will be updated as we get more information on Claude Mythos, so watch this space!

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