OGUsers (2021 breach) – 348,302 breached accounts

In April 2021, the account hijacking and SIM swapping forum OGusers suffered a data breach, the fourth since December 2018. The breach was subsequently sold on a rival hacking forum and contained usernames, email and IP addresses and passwords stored as either salted MD5 or argon2 hashes. A total of 348k unique email addresses appeared in the breach.