ArcadeDB before 26.9.1 contains an access control bypass vulnerability in the query_database tool exposed through the AI chat endpoints. The tool executes queries without binding the authenticated principal to DatabaseContext, causing per-type and per-bucket ACL checks to silently no-op and allowing authenticated users to read data they are explicitly denied at the per-type level. Attackers can prompt the AI assistant to execute queries against restricted types or buckets to retrieve sensitive data that would be rejected through normal query endpoints.