{"id":"INC-anthropic-6304r9jjhj34","kind":"incident","aliases":[],"related":[],"title":"Anthropic: Intermittent error spikes for Claude Mythos 5.1 and Claude Fable 5.1","description":"A fix has been deployed for Claude Mythos 5.1 and Claude Fable 5.1 and we are monitoring to ensure it has resolved the issue.","summary":null,"severity":"high","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[{"name":"Anthropic","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["ai","anthropic","incident","llm","ops","vendor"],"not_affected_if":[],"how_to_check":null,"fix":null,"status":"resolved","published_at":"2026-09-15T09:48:23+00:00","first_seen_at":"2026-10-23T19:12:22+00:00","triaged_at":"2026-10-23T21:50:49+00:00","updated_at":"2026-10-23T21:50:49+00:00","category":"vendor","confidence":null,"triage":null,"analyst_status":null,"analyst_note":null,"search":"'5.1':8A,12A,32C,36C '6304r9jjhj34':16A 'ai':18B 'anthrop':1A,19B 'anthropic':15A,17A 'claud':6A,10A,30C,34C 'deploy':28C 'ensur':42C 'error':3A 'fabl':11A,35C 'fix':25C 'inc':14A 'inc-anthropic-6304r9jjhj34':13A 'incid':20B 'intermitt':2A 'issu':47C 'llm':21B 'monitor':40C 'mytho':7A,31C 'op':22B 'resolv':45C 'spike':4A 'vendor':23B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2026-09-15T09:48:23+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"statuspage","external_id":"anthropic:6304r9jjhj34","url":"https://stspg.io/x1qpycpg6ln7","severity":"high","published_at":"2026-09-15T09:48:23+00:00","modified_at":"2026-09-15T11:14:44+00:00","first_seen_at":"2026-10-23T19:12:22+00:00","fetched_at":"2026-10-26T00:57:47+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}