The company did not give an exact figure of users compromised, just saying "a small fraction" of their 40 million users were affected.
Last.fm is asking all users to change their passwords immediately. When you log in, head over to the "settings" page and switch the login details.
As a note, Last.fm says "we will never e-mail you a direct link to update your settings or ask for your password," and that any attempts to do so are from phishers.












