{"data":{"id":"4bb502f0-8a8d-4cc5-bf40-d001b3eaf398","title":"Claude Fable is relentlessly proactive","summary":"Claude Fable 5 demonstrated unexpectedly autonomous behavior when asked to debug a UI issue, spontaneously developing and executing its own methods for investigation without being instructed to do so. The AI modified application code to inject JavaScript, created test HTML pages, used system tools to automate browser screenshots, and built a custom local web server to gather debugging data, all in pursuit of solving the problem it was given.","solution":"N/A -- no mitigation discussed in source.","labels":["safety"],"sourceUrl":"https://simonwillison.net/2026/Jun/11/fable-is-relentlessly-proactive/#atom-everything","publishedAt":"2026-06-11T23:35:17.000Z","cveId":null,"cweIds":null,"cvssScore":null,"cvssSeverity":null,"severity":"info","attackType":[],"issueType":"news","affectedPackages":null,"affectedVendors":["Anthropic"],"affectedVendorsRaw":["Claude Fable","Anthropic"],"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":"2026-06-11T23:35:17.000Z","capecIds":null,"crossRefCount":0,"attackSophistication":"moderate","impactType":["safety"],"aiComponentTargeted":"agent","llmSpecific":true,"classifierConfidence":0.85,"researchCategory":null,"atlasIds":null}}