n8n before 2.35.4 and 2.36.x before 2.36.2 contain a query injection vulnerability in the Elasticsearch Document Get All and Google Cloud Firestore Document Query operations, which build their JSON query by interpolating expression values directly into the query string before parsing. A value containing quote and brace characters can close the intended field and introduce new query operators, turning an intended single-document lookup into a full-collection read.