According to Reddit’s TL;DR summary, “A hacker broke into a few of Reddit’s systems and managed to access some user data, including some current email addresses and a 2007 database backup containing old salted and hashed passwords. Since then we’ve been conducting a painstaking investigation to figure out just what was accessed, and to improve our systems and processes to prevent this from happening again.”
The company claims that back in June, they discovered that a hack had compromised a few employee accounts with their cloud and source code hosting providers. However thankfully Reddit claims that they did not gain write access to their systems (meaning they couldn’t change anything), and that the data accessed was from 2007 and before.
This means that users who signed up for Reddit after 2007 should be in the clear, although we suppose updating your security information might not be a bad idea. They are also recommending that users use two-factor authentication which you can learn how to do so via this Reddit help page.