AWS Bedrock will require sharing data with Anthropic for Mythos-class models

AWS Bedrock to require sharing data with Anthropic for Mythos and future models

AWS confirmed that using Anthropic's Fable 5, Mythos 5, and future models of similar capability on Bedrock requires a 30-day data retention opt-in. Data leaves AWS's security boundary and goes to Anthropic for misuse pattern detection. It's auto-deleted after 30 days unless a safety investigation or legal hold applies. The post doesn't clarify whether this is mandatory or opt-in by default, nor whether other Bedrock models are affected.

Why it matters: Bedrock users have treated AWS's data boundary as a default security guarantee. Anthropic now mandates 30-day data handover for Mythos-class models, punching a hole in that assumption. This matters for enterprise procurement, but the source is an HN discussion thread without t...