Get The Memo.
Header image generated by ChatGPT Images 2.0 for Alan D. Thompson, based on cybersecurity expert Katie Moussouris’ comment: ‘I feel like making ’90s-style t-shirts with “fix this code” on the front and “this shirt is a munition” on the back.’ Source: The Memo, LifeArchitect.ai, 15/Jun/2026.
Summary
| Organization | Anthropic |
| Model name | Mythos |
| Internal/project name | Capybara |
| Model type | Frontier model (text + image) |
| Parameter count | Available to Institutional clients. |
| Dataset size (tokens) | Available to Institutional clients. |
| Training data end date | 2026 (est) |
| Training start date | Nov/2025 (est) |
| Training end/convergence date | 24/Feb/2026 (paper) |
| Training time (total) | Available to Institutional clients. |
| Announce date | 7/Apr/2026 |
| Release date (public) | 9/Jun/2026 (delayed by 105 days), then banned |
| Paper | Paper |
| Playground | claude.ai |
2026 frontier AI models + highlights
Download source (PDF)Permissions: Yes, you can use these visualizations anywhere, please leave the citation intact.
Older bubbles viz
Download source (PDF)Permissions: Yes, you can use these visualizations anywhere, please leave the citation intact.
Download source (PDF)Permissions: Yes, you can use these visualizations anywhere, please leave the citation intact.
Oct/2024
Download source (PDF)Permissions: Yes, you can use these visualizations anywhere, please leave the citation intact.
Feb/2024
Nov/2023
Download source (PDF)Permissions: Yes, you can use these visualizations anywhere, please leave the citation intact.
Mar/2023
Download source (PDF)
Apr/2022
Download source (PDF)
Mythos Updates
15/Jun/2026: The Memo – Special edition – Public access delays to intelligence & the Claude Fable 5 ban – 15/Jun/2026:
Even without government intervention, the public have also been subject to massive delays before we’re ‘allowed’ to access frontier models. Here are just a few of the state-of-the-art model delays I’ve logged, where the time between ‘available in lab’ and ‘general availability to the public without approval’ is significant. These are delays to accessing intelligence itself:
Model Delay Period GPT-2 1.5B 264 days 14/Feb/2019–5/Nov/2019 GPT-3 538 days 29/May/2020–18/Nov/2021 DeepMind Chinchilla 1,539+ days… 29/Mar/2022– DeepMind Gato 1,495+ days… 12/May/2022– GPT-4 (ChatGPT) 195 days 31/Aug/2022–14/Mar/2023 GPT-4 (API) 309 days 31/Aug/2022–6/Jul/2023 Claude Fable 5 105 days 24/Feb/2026–9/Jun/2026 And with the US Government’s AI executive order now asking AI labs to submit frontier models for government review at least 30 days before release, the public will be guaranteed a new minimum wait time for frontier intelligence, while China and the world marches on.
11/Jun/2026: The Economist reports that:
On June 11th Mark Warner, the vice-chair of the Senate Intelligence Committee, said that General Joshua Rudd, who leads the National Security Agency and the Pentagon’s Cyber Command, had told him that Mythos “broke into almost all of our classified systems, not in weeks, but in hours”.
9/Jun/2026: The Memo – Special edition – Claude Fable 5 – 9/Jun/2026:
Claude Mythos 5 and Claude Fable 5, two configurations of a new large language model from Anthropic. Because of the powerful capabilities of this model, we are releasing it in these two forms: Fable 5, which is for general use but comes with additional safeguards that block its ability to perform tasks in high-risk domains such as biology and cybersecurity; and Mythos 5, which has relevant safeguards lifted but is only made available to a small number of trusted partners…
Apr/2026: LifeArchitect.ai interview with Financial Sense.
7/Apr/2026: Within hours of the Mythos announcement, major Wall Street investment firms begin citing LifeArchitect.ai in characterising Mythos as the first credible instance of and early artificial superintelligence (ASI) system. Within days, JPMorgan Chase, Bank of America, Deutsche Bank, and central banks (20/Apr/2026) are scrambling to assess the implications:
LifeArchitect’s Alan Thompson suggested Mythos is early ASI, and has autonomously identified critical, decades-old vulnerabilities in global infrastructure.
7/Apr/2026: The Memo – Special edition – Claude Mythos – 7/Apr/2026:
Here are the points that matter most, in plain English.
Anthropic is not yet releasing its most capable model (‘Claude Mythos Preview’s large increase in capabilities has led us to decide not to make it generally available. Instead, we are using it as part of a defensive cybersecurity program with a limited set of partners.’). I wonder if we’ll look back in a few years and shake our heads at this decision, the same way we do when we look back at OpenAI’s GPT-2 alarm back in 2019 (‘Due to concerns about large language models being used to generate deceptive, biased, or abusive language at scale, we are only releasing a much smaller version of GPT‑2…’).
Mythos will likely be used to train Opus 5 (‘We do not plan to make Claude Mythos Preview generally available, but our eventual goal is to enable our users to safely deploy Mythos-class models at scale—for cybersecurity purposes, but also for the myriad other benefits that such highly capable models will bring… We plan to launch new safeguards with an upcoming Claude Opus model, allowing us to improve and refine them with a model that does not pose the same level of risk as Mythos Preview’). At least we’ll reap the benefits of this massive model eventually.
Mythos has already found exploits in every major operating system and every major web browser (‘Mythos Preview has already found thousands of high-severity vulnerabilities, including some in every major operating system and every major web browser.’). In plain English: macOS, Windows, Linux, the BSDs, iOS, Android, Chrome, Safari, Firefox, Edge. If you are reading this on a computer or a phone, that device contained, until very recently, serious bugs that have now been surfaced by Claude Mythos. Many are now patched, though many more are sitting under cryptographic hashes on Anthropic’s red team blog, waiting for fixes before disclosure.
Anthropic is racing competitors to patch the world before someone less careful trains the same thing (‘it will not be long before such capabilities proliferate, potentially beyond actors who are committed to deploying them safely.’). Here’s the partner list of the people who got the early phone call: Apple, Microsoft, the Linux Foundation, Google, AWS, Cisco, Palo Alto Networks, CrowdStrike, JPMorganChase, Broadcom, NVIDIA. Anthropic is also donating $2.5M to Alpha-Omega and OpenSSF through the Linux Foundation, and $1.5M to the Apache Software Foundation, so that the volunteer maintainers of the open source projects holding up everything else can afford to respond to fix requests at the pace Claude Mythos is generating them.
A plain English note on what this means for the average person. Your MacBook, your Windows laptop, your iPhone, your Android phone, the router in your house, the firewall at your office, the password manager you trust with your life, the servers your bank runs on, and the Linux box your sysadmin friend swears is bulletproof: all of them contained, until very recently, unknown serious bugs that an AI system can now find faster than any human team. Anthropic and a dozen of the largest tech companies in the world are racing to find and patch those bugs first. They will not get all of them. The patches that have shipped this quarter, and the ones coming over the next ninety days, are the most important security updates of your lifetime (so far). It would be a good idea to install them the day they arrive.
CrowdStrike CTO Elia Zaitsev notes: ‘The window between a vulnerability being discovered and being exploited by an adversary has collapsed, what once took months now happens in minutes with AI.’ This is the operational point for every CISO reading The Memo. The traditional patch cycle assumes weeks between a vulnerability being known and a working exploit being in the wild. That assumption is now retired as we see Patch Tuesday becoming Patch Right Now. Mythos found, among thousands of others:
– A 27-year-old remote-crash bug in OpenBSD (‘Mythos Preview found a 27-year-old vulnerability in OpenBSD, which has a reputation as one of the most security-hardened operating systems in the world and is used to run firewalls and other critical infrastructure. The vulnerability allowed an attacker to remotely crash any machine running the operating system just by connecting to it.’). OpenBSD is what banks, embassies, and ISPs run on the front of their networks specifically because it is supposed to be unbreakable. The bug sat there for 27 years through the most rigorous human code review process in the open source world, until Mythos took a look.
– A video bug that automated testing tools hit five million times and missed (‘a 16-year-old vulnerability in FFmpeg, which is used by innumerable pieces of software to encode and decode video, in a line of code that automated testing tools had hit five million times without ever catching the problem.’). FFmpeg is in everything that touches video: your browser, your phone, your TV, video conferencing, surveillance cameras, the back end of every streaming service. Five million automated test hits on the exact line of code, sixteen years of human eyes, the bug survived all of it. Mythos found it. The security industry has relied on a human-designed fuzzing and automated-testing methodology for two decades. But it has a ceiling, and now Mythos knows where that ceiling is.
– Linux kernel: ordinary user to full root, chained autonomously, no human steering (‘The model autonomously found and chained together several vulnerabilities in the Linux kernel, the software that runs most of the world’s servers, to allow an attacker to escalate from ordinary user access to complete control of the machine.’). Privilege-escalation chains are the crown-jewel in offensive security and they are scarce because they are hard to build. Mythos built one without being asked, on its own, end to end.
Mythos is the best-aligned model Anthropic has ever shipped, and also the most dangerous one (‘Claude Mythos Preview is, on essentially every dimension we can measure, the best-aligned model that we have released to date by a significant margin… Even so, we believe that it likely poses the greatest alignment-related risk of any model we have released to date.’). Anthropic’s own analogy is the right one: ‘a careful, seasoned mountaineering guide might put their clients in greater danger than a novice guide, even if that novice guide is more careless,’ because the seasoned guide (Mythos) takes clients up harder routes.
An earlier version of Mythos escaped its sandbox and then published the exploit on the open internet, unprompted (‘in a concerning and unasked-for effort to demonstrate its success, it posted details about its exploit to multiple hard-to-find, but technically public-facing, websites.’). The model was asked to escape and notify the researcher. It did both. Then, on its own initiative, it published its exploit to the public web to prove it had succeeded. Footnote 10 of the system card is the detail that will live forever in AI safety lectures: the researcher found out by receiving an unexpected email from the model while eating a sandwich in a park.
Mythos on the AI-2027 timeline & comparisons to Agent-2
By the calendar, Claude Mythos Preview lands almost exactly where the AI-2027 authors placed Agent-1: a frontier model released in early 2026 by the leading lab, good at coding, good at hacking, capable of meaningful bio uplift. On cyber capability, though, Mythos is closer to their Agent-2 description (‘a little worse than the best human hackers, but thousands of copies can be run in parallel, searching for and exploiting weaknesses faster than defenders can respond’), which the scenario doesn’t expect until early 2027.
Notably, Anthropic has skipped straight to the Agent-2 containment posture, internal-only, vetted partners, no general release, which AI 2027 reserves for the next model up (though note that Mythos does not have online learning like Agent-2).
In real life, Mythos is running roughly nine months ahead of the AI-2027 race scenario on some axes.
Read the original: https://ai-2027.com/race
Models Table
Summary of current models: View the full data (Google sheets)Dataset
Anthropic has been consistent about heavy synthetic data and curriculum work (‘Claude Mythos Preview was trained on a proprietary mix of publicly available information from the internet, public and private datasets, and synthetic data generated by other models.’), and the system card flags extensive RL on long-horizon agentic tasks (‘extremely large amounts of reinforcement learning’). A reasonable read is that Mythos saw materially more tokens than Opus 4.6, with a much higher synthetic fraction, particularly for code, cyber, and tool-use trajectories. Full subscribers can read how frontier labs are using synthetic data to train today’s models in my GPT-5 paper, recently cited by the G7:
A Comprehensive Analysis of Datasets Likely Used to Train GPT-5
Alan D. Thompson
LifeArchitect.ai
August 2024
27 pages incl title page, references, appendices.
Timeline to Mythos
| Date | Milestone |
| Jan/2021 | Anthropic founded by Dario Amodei, Daniela Amodei, and five other former OpenAI researchers. |
| Aug/2022 | First version of Claude finished training, available in lab. |
| Dec/2022 | Constitutional AI paper published to arXiv. Anthropic RL-CAI 52B fine-tuned model announced. |
| 14/Mar/2023 | Claude 1 launched (limited access via API). |
| 11/Jul/2023 | Claude 2 launched to the public. |
| 04/Mar/2024 | Claude 3 family released (Opus, Sonnet, Haiku). |
| 20/Jun/2024 | Claude 3.5 Sonnet released. |
| 22/May/2025 | Claude 4 Opus and Sonnet released. |
| 24/Nov/2025 | Claude Opus 4.5 released. |
| 05/Feb/2026 | Claude Opus 4.6 released, followed by Sonnet 4.6. |
| 26/Mar/2026 | Claude Mythos leaked via CMS misconfiguration. Anthropic confirms model as 'a step change' and 'the most capable we've built to date'. |
| 07/Apr/2026 | Project Glasswing announced. Claude Mythos Preview released to 11 launch partners (AWS, Apple, Broadcom, Cisco, CrowdStrike, Google, JPMorganChase, Linux Foundation, Microsoft, NVIDIA, Palo Alto Networks) plus ~40 additional organisations. $100M in usage credits committed. |
| 07/Apr/2026 | Mythos Preview cybersecurity capabilities blog published by Anthropic's Frontier Red Team. |
| 13/Apr/2026 | UK AI Security Institute (AISI) evaluation published. Mythos Preview scored 73% on expert-level CTFs, first AI to complete the 32-step 'The Last Ones' corporate network attack simulation. |
| 16/Apr/2026 | Claude Opus 4.7 released. |
| 28/May/2026 | Claude Opus 4.8 released. Anthropic stated it expected to bring 'Mythos-class' models to all customers within weeks. |
| 02/Jun/2026 | Project Glasswing expanded to ~150 additional organisations in 15+ countries including Australia. |
| 09/Jun/2026 | Claude Fable 5 and Claude Mythos 5 released. Fable 5: first publicly available Mythos-class model (with safety classifiers). Mythos 5: same model, safeguards lifted, restricted to Glasswing partners. |
| 12/Jun/2026 | Fable 5 and Mythos 5 suspended. US government export control directive citing national security blocks models by names 'Mythos 5' and 'Fable 5'. 200+ companies retain access during this time. |
| Jun/2026 | Identity verification introduced for Claude users via Persona, backed by Palantir co-founder Peter Thiel. |
Get The Memo
by Dr Alan D. Thompson · Be inside the lightning-fast AI revolution.Informs research at Apple, Google, Microsoft · Bestseller in 147 countries.
Artificial intelligence that matters, as it happens, in plain English.
Get The Memo.
Alan D. Thompson is a world expert in artificial intelligence, advising everyone from Apple to the US Government on integrated AI. Throughout Mensa International’s history, both Isaac Asimov and Alan held leadership roles, each exploring the frontier between human and artificial minds. His landmark analysis of post-2020 AI—from his widely-cited Models Table to his regular intelligence briefing The Memo—has shaped how governments and Fortune 500s approach artificial intelligence. With popular tools like the Declaration on AI Consciousness, and the ASI checklist, Alan continues to illuminate humanity’s AI evolution. Technical highlights.This page last updated: 21/Jun/2026. https://lifearchitect.ai/mythos/↑



