Breach date: 2014-09-07. Added to this index: 2014-09-12. Accounts affected: about 1.2M. Domain: forum.btcsec.com.
In September 2014, news broke of a massive leak of accounts from Yandex, the Russian search engine giants who also provides email services. The purported million "breached" accounts were disclosed at the same time as nearly 5M mail.ru accounts with both companies claiming the credentials were acquired via phishing scams rather than being obtained as a result of direct attacks against their services.
Breach data sourced from Have I Been Pwned, used under CC BY 4.0. Additional breach metadata provided by XposedOrNot. DataExposed is an independent service and is not affiliated with or endorsed by either.
The Yandex Dump breach exposed Email addresses, Passwords. About 1.2M accounts were affected.
Run the free email breach check with the address you used on that service. It will tell you whether your address appears in this dataset.
Change the password on that account and everywhere you reused it, then turn on two-factor authentication. Passwords from this breach are traded and tried automatically against other sites.