Anthropic's Claude Mythos Leak Just Shocked Everyone

The Claude Miphos leak from Anthropic just shocked everyone. So Anthropic accidentally leaked their most powerful AR model ever, and they didn't mean to. Claude Miphos, a model that Anthropic's own internal documents call, and I'm quoting directly here, by far the most powerful AR model we've ever developed, and here's what happened. A configuration error in Anthropic's content management system left nearly 3,000 unpublished documents sitting in a public searchable data store.

No password, no authentication, just there. Security researcher Roy Paz from Layer X Security and Exalinger Powles from the University of Cambridge stumbled onto it. Fortune reviewed the documents, suddenly the whole world knew about a model that Anthropic hadn't even announced yet, and this is called Claude Miphos, and it's based on everything in those leaked documents. So this model is supposed to be in a totally different league, and let me explain what Miphos actually is and why it matters to you right now.

So right now Anthropic has three tiers, Haiku, Sonnet, and Opus. Miphos doesn't fit into that structure. It's a fourth tier sitting above Opus under the internal code name Capybara. The leaked draft said directly, Capybara is a new name for a new tier of model, larger, more intelligent than our Opus models, which were until now our most powerful.

Now Claude Opus already leads the industry. It hit 76.8% on SWE Bench Verified, the benchmark that tests real software engineering tasks. It beat GPT 5.2 Codex, and Miphos scores dramatically higher than that across coding, academic reasoning, and problem solving. Dramatically, right?

Their words. Here's what sets Miphos apart technically too. Previous Claude models respond to you one step at a time, right? You ask it, it answers, ask again, it answers again.

Miphos plans and actually executes sequences of actions on its own, so it's a lot more autonomous as an AI agent, right? It can move across systems, it can make decisions, and completes operations without you waiting for you to tell it what to do next. That's a shift here, and it's an agent that actually runs itself. Think about what that means for running a business, for example.

A freelancer running client outreach today still has to check back, prompt again, review, and adjust, right? With a model like Miphos, you set the goal and it works through the steps without hand-holding. That's a totally different type of AI completely. Also, because the implications for how you build workflows, automate your business, and get results, well, these change everything, right?

They get much bigger from here. So stay with me, because Anthropic actually confirmed the model exists too. Their spokesperson said, we're developing a general purpose model with meaningful advances in reasoning, coding, and cybersecurity. Given the strength of its capabilities, we're being deliberate about how we release it.

We consider this model a step change, and the most capable we've built to date. So they're being very careful, they're being very deliberate, because here's the part of the story that surprised even the people following AI closely. Miphos is so capable in certain areas that Anthropic is privately warning senior US government officials. According to Axios, Anthropic briefed top officials with a warning.

Miphos makes large-scale attacks significantly more likely in 2026. Agents running at this capability level can plan and carry out complex operations with very little human involvement. Anthropic is literally scared of their own model. They're so concerned they haven't set a public release date.

Part of the reason is compute too, so Miphos is very expensive to run at scale, but they're working on making it more efficient. But the bigger reason is they're just being careful about who gets access and how. And this is where I want you to zoom out for a second. Look at the trajectory here.

In September 2025, a Chinese state-sponsored group used an earlier Claude model, not Miphos, a much older version, to carry out 80 to 90 percent of a coordinated campaign on its own across 30 organizations, right? Tech companies, financial institutions, government agencies, and Anthropic caught it down, shut it down, notified the organizations, but that was with the old model, not even Miphos. And now they've built something dramatically more powerful. The fact that Anthropic is warning the government before public release tells you something about where we are, right?

They built something capable enough that they're slowing down to figure out how to release it safely. And this is exactly the time to be paying attention to AI here, because every time a new model tier drops, the businesses using AI well will leap ahead of the ones that aren't. Quick pause here. If you want to be one of the businesses that knows how to use models like Claude Miphos, the moment it goes live, come join us in the AI Profit Boardroom.

We've already built out a 30-day roadmap specifically around Claude and agentic AI workflows, how to set up background agents, how to automate your outreach, your content, your client delivery. And when Miphos drops publicly, we'll be walking you through exactly how to plug it into your business, step-by-step, four coaching calls every week, daily tutorials, 2,700 members, a lot of them in there already running Claude-based AI automations for getting customers, generating leads, automating client work. And there's a full prompt library too. There's also a member map so you can find and connect with other members need you.

Link in the comments description or go to the AIprofitboardroom.com. Now back to Miphos. Let me tell you what the benchmark scores actually mean in plain terms, right? So Claude opened 4.6 The current best public model already outperforms every competitor on complex software tasks.

Miphos scores dramatically higher across coding, academic reasoning, and problem solving. That word dramatically is doing a lot of work. This isn't a minor version bump. The leaked documents treat this as a totally new class of model.

On the reasoning side, for example, Miphos actually extends what Anthropic introduced with Claude 3.7 Sonnet, which is extended thinking. That's where the model thinks through complex problems step-by-step before giving you an answer. It plans, it backtracks, it self-corrects. Miphos takes that much further, right?

So what does that look like in practice, for example? Well, a business owner doing competitive research today still has to prompt, still has to review, still has to summarize and restructure. With Miphos level agents, you describe what you want to know and the agent figures out how to get it. Multiple steps, multiple sources, done without you babysitting it.

That's the real unlock. Not just faster answers, actual autonomous workflows. And here's what most people are missing in the coverage of this leak. Anthropic internally described Miphos as being currently far ahead of any other AI model in cyber capabilities.

The leak says it presages on upcoming waves of models that can exploit vulnerabilities in ways that far outpace defenders. That's a huge statement and it caused immediate market movement. In fact, CrowdStrike, Palo Alto, Networks, Zscaler, Fortinet all saw their share prices drop after the Miphos news. Investors started asking if Frontier AI can outperform entire security teams.

What does that mean for the companies selling security subscriptions? And that's the signal in the story. When a model is powerful enough to move a market before it's even been released, you're watching something real. You're watching something change and shift in the world.

Now, Miphos isn't public yet. There's no release date. Anthropic is testing it with a small group of early access customers. They're working on making it cheaper to run.

The compute requirements right now are very expensive too. But here's the thing about Anthropic's release history. When Opus 4.6 came out, people who had been building cloud workflows were immediately able to plug it in. Their automations got better overnight.

Their client results improved. The people who had done nothing, they had nothing to plug it into. And that's a gap between being prepared and being unprepared. Because businesses will grow every single new time a model like this drops if you're already using learning how to use AI automation.

So Miphos is coming. The leak confirmed it. Anthropic confirmed it. The only question is whether you'll be ready to use it when it does.

The businesses that move first on every new cloud tier are the ones compounding results. Every new model drops and they get better. The rest are still catching up from the last one. And you don't have to be a developer to use this stuff, right?

An agency owner, for example, could just use cloud today to automate their proposal writing, their client onboarding, their SEO content pipeline. When Miphos lands with autonomous multi-step execution, those same workflows become dramatically more powerful. That's the trajectory and it's not slowing down. One more thing from the leak.

Alongside the Miphos documents, the exposed cash also revealed plans for an invite-only CEO summit in Europe. Anthropic is actively selling enterprise access to Miphos to large corporate customers. They're moving fast on the enterprise side. The businesses that understand this model and know how to use it will have a real advantage in conversations with clients who don't.

And here's where things are heading. Anthropic have now confirmed they're building tiers above Opus. Miphos adds a fourth tier. The Haiku Sonic Opus structure had a ceiling and they blew way past it.

And based on the pattern we've seen, Opus 4.5, then 4.6, beating every competitor already. Whatever comes after Miphos will be even further ahead. The acceleration isn't stopping. The models keep getting better.

The agents keep getting more autonomous. And the only question is, what are you going to do about it now? If you want a step-by-step system for using cloud and the latest AI agents in your business before Miphos even drops publicly, the AI Profit Boardroom is where to start. Inside, we've already got tutorials walking you through how to build cloud-based workflows for lead gen, content, and client delivery.

When Miphos goes live, you'll be in the group that's first to know how to use it. We've got 2,700 members in there running AI automation in their businesses right now for coaching calls every week, daily tutorials, 30-day roadmaps, and a full prompt library, and a member map so you can connect with people near you who are already doing this. Link in the comments description or go to the AIProfitBoardroom.com. Claude Miphos leaked.

Anthropic confirmed it. A new tier above Opus with autonomous multi-step execution, dramatically higher benchmarks, and capabilities powerful enough that Anthropic is warning the government before it releases. This is the most capable Claude ever built. And it's coming.

Get ready.