Mythos Fable 5 benchmarks are impressive. Additionally, Claude Mythos 5, a separate model version with enhanced safeguards, has been released to a small group of cyber defenders and infrastructure providers.
SAFETY
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Risk of Account Suspension Using Public Fable 5 Model
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Yeah, try doing it with the public Fable 5 model and you will be flagged for "security reasons" and your account could potentially get suspended. :/
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Suspicion that Anthropic’s safety measures are performative
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Starting to suspect that Anthropic's putative security and safety considerations are largely posturing and performative.
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Claude-Fable-5 refuses a third of questions on BullshitBench
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Claude-Fable-5 on BullshitBench: it refused a THIRD of questions (with multiple attempts). Excluding refusals, it performed well, worse than some other Claude models (chart below).
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AI model predicts fire spread, redirects evacuees to safer exits
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#AI model predicts building fire spread, redirecting evacuees to safer exits in real time
by National Institute of Standards and Technology @TechXplore_com Learn more: https://
bit.ly/4xcBdwo #ArtificialIntelligence #EmergingTech #Innovation #Technology #Tech -
Anthropic’s guardrail concerns versus model unusability regrets
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I understand that Anthropic's concerns about the model being misused without guardrails are significant. And I take that seriously. We're talking about a technology with unforeseen potential. However, the fact that it was, in some cases, literally unusable is regrettable.
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The importance of self-verification loops in the era of powerful models
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We talk a lot about how important it is to set up self-verification loops. Especially in the age of powerful models that can run for long periods of time, self-verification is a key ingredient that enables the model to run for much longer, delivering a result that is closer to… https://t.co/NHiral0F9j
— Boris Cherny (@bcherny) 9 juin 2026We talk a lot about the importance of setting up self-verification loops. Especially in the era of powerful models that can operate for long periods, self-verification is a key ingredient that allows the model to function much more
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Model now limited, previously considered dangerous
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"pEr0 Sí hAcE 2 MeSeS deCIAn eRa P€ligRos0…" Leaving aside the fact that 2 months ago they didn't have enough computing power to release it, IN ADDITION, the model they released today is limited, precisely solving these security issues. You have read
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LLM shadow-banning was not planned for 2026
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The shadow-banning of LLM development was certainly not on my bucket list for 2026.
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Anthropic’s new Fable 5 safeguards quietly limit effectiveness
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Anthropic’s new Fable 5 safeguards are fascinating. When the model is used for frontier LLM development, it apparently does not simply refuse or warn the user. Instead, it quietly limits its own effectiveness through techniques like prompt modification, steering vectors, and