Interesting that the ARRL appears to be playing down the situation, calling it a disruption and essentially only public data being stored.
ARRL Systems Service Disruption
05/17/2024
Updated 5/17/2024
Some members have asked whether their personal information has been compromised in some way. ARRL does not store credit card information anywhere on our systems, and we do not collect social security numbers. Our member database only contains publicly available information like name, address, and call sign along with ARRL specific data like email preferences and membership dates.
Original story below: 5/16/2024
We are in the process of responding to a serious incident involving access to our network and headquarters-based systems. Several services, such as Logbook of The World® and the ARRL Learning Center, are affected. Please know that restoring access is our highest priority, and we are expeditiously working with outside industry experts to address the issue. We appreciate your patience.
This story will be updated with new developments.
Source: https://www.arrl.org/news/arrl-systems-service-disruption