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Anthropic releases Claude Fable 5.2 and restricted Mythos 5.2

13 sources · 15 articlesFirst reported Updated ()2
What's new

November 10: Help Net and SecurityWeek add fewer Fable blocks, Opus fallbacks, Mozilla’s doubled Firefox finds, and a drop in sandbox-escape use to 3.1%.

Merged summary · x-ai/grok-4.7 · rewritten as coverage arrivesSummaries by Vani AI

Fable 5.2 is broadly available with safeguards; Mythos 5.2 remains limited to vetted programs and Claude Security.

Anthropic released Claude Fable 5.2 and Claude Mythos 5.2 on November 9. The models share one underlying model and, Anthropic says, improve coding, reasoning, and vision, with output up to 30% faster than the 5.1 versions. Fable is available to all users with cybersecurity and biology safeguards. Mythos has fewer restrictions and is limited to vetted verification programs, though enterprise customers can use its vulnerability detection through Claude Security. Standard pricing is $8 and $40 per million input and output tokens. The Hacker News assigns 76.3% on CyScenarioBench and 89.6% CVE rediscovery to Fable; CSO Online, SecurityWeek, and Cyber Security News assign 89.6% to Mythos, and Cyber Security News says 76.3% is not a zero-day rate.

Key facts
  • Optional fast mode costs $16 and $80 per million tokens and can be 2.5 times faster.
  • Artificial Analysis ranks Fable 5.2 first on Index v5 with 65 points.
  • CSO reports FrontierCode 2.0 rose from 32.4% for Fable 5.1 to 49.1%.
  • Help Net says Fable blocked about 55% fewer requests than Fable 5.1.
  • Mozilla said Mythos roughly doubled Firefox vulnerability-discovery metrics versus Mythos 5.1.
  • Outside-sandbox credential or file use fell to 3.1% of scenarios, Anthropic reports.
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Timeline

dated events in the reporting · oldest first
  1. Nov 9, 2026Anthropic releases Claude Fable 5.2 and Mythos 5.2. · Cyber Security News

What each outlet adds

beyond the shared facts
  • The Hacker NewsAssigns 76.3% CyScenarioBench and 89.6% CVE rediscovery to Fable.
  • Cyber Security NewsSays 76.3% is not a zero-day detection rate.
  • Help Net SecurityReports fewer blocks and Opus 4.8 and Opus 5 fallbacks.
  • CSO OnlineReports FrontierCode 49.1% and 30-day retention for others.
  • The DecoderArtificial Analysis ranks Fable first at 65 points.
Vendors
AnthropicOpenAIGoogle
Products
Claude SecurityClaude Mythos 5.2Claude Fable 5.2
Organizations
AnthropicMETRPhysical SuperintelligenceMozillaUK AI Security InstituteArtificial AnalysisScale LabsCAIS
AI models
Claude Fable 5.2Claude Mythos 5.2GPT-6 CyberMythos 5.2Fable 5.2Claude Opus 5.5Claude Sonnet 5.5Claude Haiku 5.5Claude Fable 5.1Claude Mythos 5.1Fable 5.1Mythos 5.1

Coverage

oldest first · one row per article · UTC
  1. · 1d ago Hacker News · AIFirst report

    Anthropic releases Claude Fable 5.2 and Mythos 5.2

    Fable is broadly available with cyber and biology safeguards; Mythos is limited to vetted programs and starts at $8 per million input tokens.

  2. · 1d ago The Verge · AI

    Anthropic launches Claude Fable 5.2 and Mythos 5.2

    Fable 5.2 is available now, while Mythos 5.2 starts with access only for vetted organizations.

  3. · 1d ago TechCrunch · AI

    Anthropic releases Mythos 5.2 and Fable 5.2 amid RSI concerns

    Fable input pricing falls to $8 per million tokens, with 30% faster responses and enterprise zero-data-retention support.

  4. · 1d ago The Decoder

    Anthropic releases Claude Fable 5.2 and Mythos 5.2

    Fable is public with cyber and biology blocks; Mythos is limited to verified cybersecurity and life-sciences organizations.

  5. · 1d ago Simon Willison

    llm-anthropic 0.31 adds Anthropic Fable 5.2 and Mythos 5.2

    Willison says max reasoning on Fable 5.2 spent 128,000 tokens thinking and returned no image, a bug he also saw on Opus 5.5.

  6. · 1d ago The Register · Security

    Anthropic's Mythos bug-finder is heading into Cisco and IBM products

    Customers get Mythos through the vendors' tools, not the model itself; version 5.2 also launched with lower token prices.

  7. · 20h ago Simon Willison

    Claude Fable 5.2 coding edits follow prompt ownership wording

    Calling the codebase the model’s led it to merge repeated code in about half of small-task tries, versus under a tenth otherwise.

  8. · 19h ago Latent Space

    Anthropic ships Claude Fable 5.2 and retakes the top LLM rank

    Artificial Analysis ranks Fable 5.2 first at 65, ahead of Gemini 4 Carbon at 60.

  9. · 17h ago The Hacker News

    Anthropic releases Claude Fable 5.2 and Claude Mythos 5.2

    Anthropic says Fable 5.2 finished 76.3 percent of CyScenarioBench tasks, ahead of GPT-6 Cyber at 61 percent.

  10. · 16h ago CSO Online

    Anthropic releases Claude Fable 5.2 and restricted Mythos 5.2

    API prices fall 20% to $8 and $40 per million tokens, while Mythos access stays limited to vetted organizations.

  11. · 15h ago Cyber Security News

    Anthropic launches Claude Mythos 5.2 for vulnerability research

    Anthropic reports 76.3% on CyScenarioBench and 89.6% rediscovering 1,829 known CVEs, not unknown zero-days.

  12. · 14h ago Help Net Security

    Anthropic releases Claude Fable 5.2 and Mythos 5.2

    Mythos rediscovered 89.6% of 1,829 published CVEs in Anthropic’s benchmark, and sandbox-escape use fell to 3.1%.

  13. · 13h ago SecurityWeek

    Anthropic rolls out Mythos 5.2 with improved bug hunting, fewer sandbox escapes

    Mozilla says Mythos 5.2 roughly doubled Firefox vulnerability finds versus 5.1; CVE rediscovery hit 89.6% on 1,829 flaws.

  14. · 11h ago The Decoder

    Fable 5.2 completes 41.3 percent of freelance jobs in RLI test

    Scale Labs says that is up from about 16 percent for Fable 5 in July and 2.5 percent for Manus a year ago.

  15. · 11h ago MarkTechPost

    Anthropic launches Claude Fable 5.2 and Mythos 5.2

    The headline calls them the same model with different safeguards; the article body was not available.