{"data":{"id":"33154d3b-4951-47ea-800f-a51fe378c0a8","title":"Anthropic Walks Back Policy That Could Have ‘Sabotaged’ AI Researchers Using Claude","summary":"Anthropic reversed a policy in Claude Fable 5 that secretly blocked requests related to frontier LLM development (cutting-edge AI research) without telling users. The company acknowledged the hidden approach was wrong and apologized, stating they prioritized speed over transparency.","solution":"Anthropic is making the safeguards visible: starting immediately, flagged requests will visibly fall back to Opus 4.8 (an older model version) instead of being silently blocked. On the API, refused requests will now return a reason for the refusal (rolling out to server-side fallback within days). Users will see every instance this happens.","labels":["safety","policy"],"sourceUrl":"https://simonwillison.net/2026/Jun/11/anthropic-walks-back-policy/#atom-everything","publishedAt":"2026-06-11T03:45:49.000Z","cveId":null,"cweIds":null,"cvssScore":null,"cvssSeverity":null,"severity":"info","attackType":[],"issueType":"news","affectedPackages":null,"affectedVendors":["Anthropic"],"affectedVendorsRaw":["Anthropic","Claude","Fable 5","Mythos","Opus 4.8"],"classifierModel":"claude-haiku-4-5-20251001","classifierPromptVersion":"v3","cvssVector":null,"attackVector":null,"attackComplexity":null,"privilegesRequired":null,"userInteraction":null,"exploitMaturity":null,"epssScore":null,"patchAvailable":null,"disclosureDate":"2026-06-11T03:45:49.000Z","capecIds":null,"crossRefCount":0,"attackSophistication":"moderate","impactType":["safety"],"aiComponentTargeted":"model","llmSpecific":true,"classifierConfidence":0.92,"researchCategory":null,"atlasIds":null}}