while Lev Leviev sold his 8% share in the same deal, giving United Capital Partners 48% ownership.
The breach notification confirmed that it has added the breached data into its database, alongside another 2.3 million records from 10 other websites that the group bundled in with its blog post.
This is the latest hack in a long line of similar attacks on out-of-date and unpatched forums with widely known and glaring security flaws.
The user base reached 1 million in July 2007, and 10 million in April 2008.
In December 2008 VK overtook rival Odnoklassniki as Russia's most popular social networking service.
Many of Mail.ru's forums ran versions of v Bulletin software dating back to early-2013.