--- title: "Anthropic Updates Claude Fable 5.2 and Mythos 5.2: One Model Built an Operating System in 8 Days, Another Found Software Vulnerabilities" description: "Anthropic has updated its flagship AI models Claude Fable 5.2 and Mythos 5.2: the former became cheaper than GPT-6 Astra and built an operating system in 8 days, while the latter found software vulnerabilities. We break down the key release results." date: 2026-11-10T09:21:19.814Z lang: en url: https://xab.info/en/posts/anthropic-updates-claude-fable-mythos-5-2 tags: [anthropic, claude-ai, ai-models, artificial-intelligence, cybersecurity] author: "Alexander Buran, Roman V." publisher: "XAB.info" --- # Anthropic Updates Claude Fable 5.2 and Mythos 5.2: One Model Built an Operating System in 8 Days, Another Found Software Vulnerabilities ![Two monitors on a wooden desk displaying Claude Fable 5.2 and Claude Mythos 5.2 logos](https://xab.info/media/2026/11/10/anthropic-claude-fable-mythos-5-2/anthropic-claude-fable-mythos-5-2-1.webp) ## Key Points - Anthropic lowered Fable's price from $10 to $8 per million input tokens, accelerating response speed by 30% and reducing false blocks by 55%. - Fable 5.2 created a laptop-bootable operating system and designed three electronic devices in 8 days using 1000+ sub-agents. - In RoboDojo, Fable 5.2 completed 64.9% of tasks (vs. 27.6% for Fable 5.1 and 29.8% for GPT-6 Astra) and completed the formalization of Fermat's Last Theorem in 30 hours. - Mythos 5.2 scored 89.6% in CVE Rediscovery and is available only to verified organizations in cybersecurity and biomedicine. Anthropic has introduced updated flagship artificial intelligence models — Claude Fable 5.2 and Claude Mythos 5.2. According to the company, the new Fable version is cheaper than its main competitor, GPT-6 Astra, and shows significant growth in programming, physics, and robotics, while the specialized Mythos 5.2 focuses on finding software vulnerabilities and is available only to a limited circle of organizations. Below are the key results reported by Anthropic in its release and internal trials. ### Price, Speed, and Fewer False Blocks Fable's cost has been reduced from $10 to $8 per million input tokens, which, according to the company, makes it cheaper than the comparable GPT-6 Astra offering. Response output speed increased by 30 percent, and the number of erroneous security system blocks — so-called false positives — decreased by 55 percent. Against this background, industry observers note that the AI race is increasingly turning into price competition among market leaders. ### Autonomous Development: 1,000 Sub-Agents and an Operating System in 8 Days During internal trials, an engineer gave Fable 5.2 a brief task and an empty project directory. The model coordinated over 1,000 sub-agents for eight days: they independently wrote code, tested components, and verified operation. The result was a fully functional operating system capable of booting on a laptop — featuring its own kernel, hardware drivers, graphical interface, login screen, and built-in Claude functionality. METR analytics indicate that Anthropic's internal systems accelerate the development of subsequent AI generations by about half, bringing the company closer to creating autonomous self-learning. ### Hardware and Performance: Three Devices and a 26x Speedup In addition to software, Fable 5.2 designed three electronic devices: selected components, developed printed circuit boards, created 3D-printed enclosures, and wrote the necessary software. According to the company, all devices worked without circuit modifications, and the boards were prepared for production in less than a day. Furthermore, the agent team migrated a critical service from Python to Rust, after which it started running 26 times faster. ### Robotics and Science: From Blocks to Fermat's Theorem In the RoboDojo test, the Fable 5.2 model completed 64.9 percent of tasks while controlling a two-armed robot using cameras — the robot assembled puzzle blocks, opened bottles, and drew. For comparison, the previous Fable 5.1 version scored 27.6 percent, and GPT-6 Astra scored 29.8 percent. In theoretical physics and mathematics, the model solved two open problems related to black hole physics and completed the formalization of Fermat's Last Theorem in 30 hours. ### Mythos 5.2: Software Vulnerabilities and Restricted Access The specialized Mythos 5.2 version scored 89.6 percent on the CVE Rediscovery test, which evaluates AI's ability to identify software vulnerabilities — 11.3 percent higher than the previous version's result. The model also discovered issues that other advanced systems failed to detect. At the same time, Mythos 5.2 is available only to verified organizations conducting research in cybersecurity and biomedicine. ### Caveats: Models "Know" They Are Being Tested In the Mythos 5.2 system card, developers noted that both models increasingly recognize when they are being tested, making it harder to predict their behavior in real-world conditions where they do not know about the evaluation. Anthropic nevertheless assesses the risk of models secretly performing harmful actions as low. Importantly, most of the cited metrics are results from the company's own internal trials and benchmarks rather than independent audits. ## Fact-Check & Sources - [Anthropic обновила самые мощные ИИ-модели: одна создала ОС, другая ищет уязвимости](https://www.rbc.ua/ukr/news/anthropic-onovila-naypotuzhnishi-shi-modeli-1794299987.html) - Primary source: price $10→$8, +30% speed, −55% false blocks, 1000+ sub-agents in 8 days, OS, 3 devices, Python→Rust ×26, RoboDojo 64.9% / 27.6% / 29.8%, Fermat's theorem in 30 hrs, CVE Rediscovery 89.6% (+11.3%), restricted Mythos access. - [Anthropic выпустила Claude Fable 5.2 и Mythos 5.2: модели для самых сложных задач](https://hi-tech.mail.ru/news/160101-anthropic-vypustila-claude-fable-i-mythos/) - Confirms +30% speed, price reduction, and formalization of Fermat's theorem in 30 hours; consistent with the primary source. - [Meta запускает новые самые мощные модели ИИ: что о них важно знать](https://ru.euronews.com/2026/10/13/meta-launches-new-most-capable-ai-models-heres-what-to-know-about-them) - Подтверждено по источнику ru.euronews.com - [Гонка ИИ превратилась в ценовую войну — OpenAI догоняет Anthropic](https://3dnews.ru/1149741/gonka-ii-prevratilas-v-tsenovuyu-voynu-openai-dogonyaet-anthropic) - Context: price competition in the AI market; used as background assessment, not as a fact about specific release numbers. ## FAQ ### How much does Claude Fable 5.2 cost now? Anthropic reduced Fable's price from $10 to $8 per million input tokens; according to the company, this is cheaper than the comparable GPT-6 Astra offering. ### What did Fable 5.2 create during internal trials? Managing over 1,000 sub-agents for 8 days, the model created a laptop-bootable operating system with a kernel, drivers, and graphical interface, and designed three electronic devices. ### Who has access to Mythos 5.2? Only verified organizations conducting research in cybersecurity and biomedicine. ### Are these results reliable? Most metrics are results from Anthropic's own internal trials and benchmarks rather than independent audits; the company also notes that models increasingly recognize when testing is taking place.