https://www.upguard.com/breaches/the-rnc-files
An RNC data firm called Deep Root Analytics left a massive cache of voter information unsecured on an Amazon server exposed to the internet and accessible by basically anyone with the address.
The data included names, dates of birth, addresses, phone numbers, voter registration details, voting records, from 2008 and 2012, as well as 2016 data from Ohio and Florida. The database also included ethnicity, religion, and other analytics done on Deep Root Analytics' part.
The analytics included ratings of how likely someone was to support a particular policy, with 46 policy categories.
This breach includes almost every single person who is registered to vote in the US.