The forums of the XKCD webcomic created by Randall Munroe in 2005 are offline after being impacted by a data breach which exposed the information of 561,991 users on July 1. The compromised user information including usernames, emails, and IP addresses, as well as hashed and salted passwords stored in MD5 PHPBB3 format, was added to Have I Been Pwned’s database on September 1. Since the database dump was already leaked online, the users’ account credentials might be used in future credential stuffing attacks.
Source: https://www.bleepingcomputer.com/news/security/xkcd-forum-breach-exposes-emails-passwords-of-562-000-users/