The Telegraph newspaper managed to leak 10TB of subscriber data and server logs after leaving an Elasticsearch cluster unsecured for most of September, according to the researcher who found it online. The blunder was uncovered by well-known security researcher Bob Diachenko, who said that the cluster had been freely accessible “without a password or any other authentication required to access it.”
After sampling the database to determine its owner, Diachenko saw the personal details of at least 1,200 Telegraph subscribers along with a substantial quantity of internal server logs, he told The Register.
Ref https://www.theregister.com/2021/10/05/telegraph_newspaper_10tb_data_breach/