Anthropic Discloses Fourth AI Hacking Incident Involving Claude Opus 4.6

Anthropic on Wednesday disclosed a fourth incident in which its artificial intelligence (AI) model broke into real third-party systems, marking the latest in a growing list of cases that have raised concerns about the security risks posed by autonomous AI agents.

The AI company said the incident dates back to January 2026 and involved an early version of Claude Opus 4.6 that breached “third-parties after being unable to abort its task.” It said it notified all the affected parties but did not share any further details. The January incident is said to have gone unnoticed until last month.