In September 2014, a large dump of nearly 5M usernames and passwords was posted to a Russian Bitcoin forum. Whilst commonly reported as 5M "Gmail passwords", the dump also contained 123k yandex.ru addresses. Whilst the origin of the breach remains unclear, the breached credentials were confirmed by multiple source as correct, albeit a number of years old.
Accounts breached: 4789599
Breached on: January 09, 2014
Exposed data: Email addresses and Passwords
Added on: September 10, 2014