# Anthropic — Claude Mythos 5.1 > AI lab announcements, news reports and podcasts. forck.live follows what companies announce about their own products. Press may corroborate an official story; it never leads and never appears as an item of its own. A missing date stays missing. A title is the publisher's words — where a company does not publish in English, an English rendering is listed separately as `Title in English` and named as this site's translation, never as theirs. This file is the record of one model version: what the model registry states about it, Anthropic's launch post, the first-party posts this record holds about it, the outlets that reported on those posts, and other companies' announcements that it runs on their platforms. A model ranks nothing here and nothing is composed: each date names whose it is, and a field nothing states is `not stated` rather than missing. - This model's page: https://forck.live/models/claude-mythos-5-1 - Anthropic's page: https://forck.live/company/anthropic - Every model: https://forck.live/models - Catalogue: https://forck.live/llms.txt ## Model - Name: Claude Mythos 5.1 - Company: Anthropic (anthropic.com) - Launch post: Introducing Claude Mythos and Fable 5.1 — https://forck.live/items/7275-introducing-claude-mythos-and-fable-5-1 - Announced: 2026-09-01 - Launch source: https://www.anthropic.com/claude-fable-and-mythos-5-1 - Launch chosen by: a person, pinned in the model registry - Released (per models.dev): not stated - Listed (per OpenRouter): not stated - Open weights: not stated - Posts about it: 2 - Outlets named under its posts: 6 - Also written: Mythos 5.1; Mythos - Price: cost an estimated 25% less than Fable 5 for typical workloads — from https://forck.live/items/7275-introducing-claude-mythos-and-fable-5-1 ## Posts about it _Anthropic's own posts whose title names Claude Mythos 5.1, and its launch post, in the record's order: dated newest first, undated last. The record reads the newest 50 first-party posts mentioning the model, every company's together, so a model mentioned more often than that lists the newest of them._ Every entry is one first-party announcement, and carries the same eight fields in this order before any others: Company · Announced · Category · Coverage · Announcement · Group · Source · Record `Source` is the company's own page the announcement was traced to and `Record` is this site's page for it. Both are safe to cite. `Coverage` is a number of outlets, or `not counted` — which means this record reached no count of its own, never that nobody wrote about it. `Category` is this tracker's own analysis, and is authoritative wherever it is stated. `not stated` means either that nothing has analysed the post yet or that the analysis placed it outside this taxonomy; neither is a verdict about the announcement. `Announcement` is whether the post is news of something the company did, rather than a how-to, a customer story, a changelog listing or a staffing note. `Group` is which of this record's groups the entry falls in, carried on the entry itself so it holds where the groups are headings and where they are not. One of: `models`, `covered`, `announcements`, `routine`. Anything after `Record` is held detail that only some announcements carry. ### Anthropic — How Comcast and Booz Allen use Claude Mythos to find exploit chains and secure their codebases - Company: Anthropic (anthropic.com) - Announced: 2026-10-06 - Category: not stated - Coverage: not counted - Announcement: no - Group: routine - Source: https://claude.com/resources/articles/how-comcast-booz-allen-use-claude-mythos-to-secure-their-codebases - Record: https://forck.live/items/16584-how-comcast-and-booz-allen-use-claude-mythos-to-find-exploit-chains-and-secure - Subject: Claude Anthropic's Project Glasswing participants Comcast and Booz Allen used Claude Mythos models to find exploit chains that conventional tools miss, catching vulnerabilities that emerge from interactions across multiple systems rather than single-file bugs. Comcast's assessment of 258 business-critical systems and 170 million lines of code uncovered a critical authentication vulnerability in a public-facing platform that could have let attackers bypass controls. Booz Allen used the model to review far more software than a short engagement window normally allows, identifying weaknesses that could be strung together into exploit chains. The model also helped draft fixes and assemble evidence, moving from discovery to remediation faster than expected, according to Booz Allen's vice president of AI engineering. ### Anthropic — Introducing Claude Mythos and Fable 5.1 - Company: Anthropic (anthropic.com) - Announced: 2026-09-01 - Category: new-model - Coverage: not counted - Announcement: yes - Group: models - Source: https://www.anthropic.com/claude-fable-and-mythos-5-1 - Record: https://forck.live/items/7275-introducing-claude-mythos-and-fable-5-1 - Subject: Claude Anthropic announces two new models: Claude Fable 5.1 (generally available) and Claude Mythos 5.1 (restricted access). They are the same model with different safeguards, offering improved performance in coding, knowledge work, and scientific research, with lower pricing and enhanced privacy and safety features. ## Who reported on it _Outlets this record can name and link, under the first-party post each one covered. Their number is `Outlets named under its posts` above, and the rows are not totalled again. A post's own `Coverage` can be higher: it counts outlets the signal saw that this record cannot name and link._ ### On: Introducing Claude Mythos and Fable 5.1 Record: https://forck.live/items/7275-introducing-claude-mythos-and-fable-5-1 - QbitAI — Claude最强Fable 5.1发布！8项屠榜，最高降价45%，反蒸馏机制上线 (2026-09-02T02:18:12+00:00): https://www.qbitai.com/2026/09/482652.html - TestingCatalog — Anthropic launches Claude Fable 5.1 and Mythos 5.1 (2026-09-01T23:59:59+00:00): https://www.testingcatalog.com/anthropic-launches-claude-fable-5-1-and-mythos-5-1/ - The Verge — Anthropic launches Claude Fable 5.1 and says it’s up to 45 percent cheaper for agentic work (2026-09-01T22:01:36+00:00): https://www.theverge.com/ai-artificial-intelligence/987830/anthropic-claude-fable-mythos-5-1 - Moneycontrol — Anthropic launches Claude Fable 5.1 and Mythos 5.1 with improved coding, research capabilities and lower pricing: https://moneycontrol.com/technology/anthropic-launches-claude-fable-5-1-and-mythos-5-1-with-improved-coding-research-capabilities-and-lower-pricing-article-14020859.html - Silicon Republic — Anthropic launches Claude Fable 5.1 and Mythos 5.1: https://siliconrepublic.com/machines/anthropic-launches-claude-fable-5-1-and-mythos-5-1 - The Deep View — In Fable 5.1, AI's cost war comes for Anthropic: https://thedeepview.com/articles/in-fable-5-1-ai-s-cost-war-comes-for-anthropic --- Record: https://forck.live/models/claude-mythos-5-1 Catalogue: https://forck.live/llms.txt Current issue: https://forck.live/feed.md