01What the Claude Mythos Leak Is
The Claude Mythos leak refers to unauthorized access to Anthropic's most powerful and unreleased AI model, Claude Mythos. A security researcher first exposed its existence in March, and later a Discord group gained actual access to the model.
Claude Mythos is so advanced that Anthropic said it was too dangerous to release publicly. It can find software bugs, including zero-day vulnerabilities, faster than any human. This leak matters because it shows how even the most restricted AI can be accessed with simple guessing.
In this episode, Julian Goldie explains exactly what happened, how the leak occurred, and what it means for the future of AI.
02How Claude Mythos Got Leaked: The Full Story
The story starts on March 26th, when a security researcher found a misconfiguration in Anthropic's content management system. This simple error exposed internal documents, including details about Claude Mythos.
Then, on April 7th, a small group on a private Discord server figured out how to get access to Claude Mythos. They did it by guessing the URL, because they had studied Anthropic's naming patterns for model endpoints. They also used credentials from a third-party contractor who works with Anthropic.
- They guessed the URL by studying previous model names.
- They used contractor credentials to log in.
- They showed screenshots and did a live demo to prove access.
Anthropic confirmed they are investigating. They said there is no evidence that core systems were touched, but the fact remains that a group of curious people got in.
03Project Glasswing and the Timeline
The leak happened on the same day Anthropic announced Project Glasswing, which is an initiative to make Claude capabilities more widely available. The timing is important because Anthropic already compressed timelines due to the earlier March leak.
Project Glasswing seems to be Anthropic's plan to eventually offer Claude Mythos-class capabilities to regular users. But the leak forced them to speed up their plans.
Julian explains that this shows how fast the AI industry is moving. Companies are trying to keep advanced models secure, but they are also struggling to do so.
The leak also highlights that even billion-dollar companies can make simple mistakes, like misconfigured systems or poor access controls.
04How to Protect Your AI Models from Leaks
This episode is not a tutorial, but you can learn from what went wrong. If you build AI products, you should avoid the same mistakes.
- Use strong, unique credentials for contractors and rotate them often.
- Do not rely on guessing-proof URLs; use multi-factor authentication.
- Monitor access logs for unusual activity, especially from third-party vendors.
- Test your content management system for misconfigurations regularly.
- Have a response plan for leaks, including public communication.
Anthropic's mistake was a simple CMS error. That shows that even the most advanced companies can overlook basic security.
If you are a user, you should be aware that your data could be exposed if a company like Anthropic has a leak. But in this case, the leak was about model access, not personal user data.
05Results and Comparisons: GPT 5.5 and Other Leaks
The episode also covers a separate leak at OpenAI. On April 22nd, some Codex users on Pro accounts saw a dropdown with unreleased model names. That leak revealed at least eight internal models, including GPT 5.5, which was briefly accessible.
Developers who used GPT 5.5 gave immediate feedback. One developer said it fixed a bug that had been stuck for four hours in about three minutes. Others said it felt significantly faster and more token efficient.
- GPT 5.5 has the internal codename SPUD and pre-training completed on March 24th.
- Greg Brockman said two years of research are baked into the model.
- Sam Altman called it a very strong model that could accelerate the economy.
Other leaked models include Arcanine, Glacier Alpha, Heisenberg, and GPT-Ruslin. Nobody knows exactly what they are for, but they show OpenAI is testing a whole fleet of models.
06Tips, Limits, and Mistakes to Avoid
Julian shares several important lessons from these leaks. First, never assume that your security is perfect. Even the biggest AI companies make errors.
- Do not rely on obscurity; guessing URLs is a real threat.
- Vendor access can be a weak point, so always review third-party permissions.
- Internal model names can reveal secrets, so keep them hidden from UI elements.
Another limit is that these leaked models are not fully tested. Developers only got brief access, so long-term reliability is unknown.
Avoid the mistake of thinking leaks are harmless. While the Discord group said they were just curious, someone with bad intentions could use this access for harm.
Finally, do not overreact to every leak. Julian says it is normal for big companies to have some leaks, given how fast they are moving.
07Who This Leak Is For and Why It Matters
This leak matters for anyone who uses AI tools, develops software, or works in cybersecurity. If you are a developer, you might benefit from models that can find bugs faster.
If you are a business owner, you should understand that AI capabilities are growing in huge steps. This could mean better tools for your business soon.
Julian also mentions that both Anthropic and OpenAI are dealing with leaks in the same week. That shows the industry is moving so fast that even the companies themselves struggle to keep up.
The bottom line is that AI is advancing faster than most people realize. These leaks give us a glimpse of what is coming next.
For regular users, this means more powerful AI is on the way, but also more security risks.
08What Happens Next: GPT 5.5 and Claude Mythos
Julian predicts that GPT 5.5 could be released very soon, possibly this week or next. He points to Sam Altman's response on X, where he saluted a user who said they would subscribe if GPT 5.5 launched on Thursday.
For Claude Mythos, Anthropic will likely have to find a way to offer similar capabilities to regular users sooner than planned. Project Glasswing is already part of that effort.
Both leaks show that the future of AI will be more powerful and more accessible. But companies will need to improve security to prevent unauthorized access.
As a user, you should stay informed about these developments, but also be cautious about trusting leaked information.
