The Elasticsearch logging provider, when configured with a `host` URL that embeds credentials (for example `https://user:password@server.example.com:9200`), wrote the full host URL — including the embedded credentials — into task logs. Any user with task-log read permission could harvest the backend credentials. Users are advised to upgrade to `apache-airflow-providers-elasticsearch` 6.5.3 or later and, as a defense-in-depth measure, configure the backend credentials via a secret backend rather than embedding them in the `[elasticsearch] host` URL.