LinkedIn has confirmed that some of the passwords that were compromised by hackers and posted on a Russian website, correspond to LinkedIn accounts and they are currently investigating. The good news is that no usernames were compromised. It is reported that approximately 6.5 million passwords have been compromised. The passwords are encrypted using SHA-1 hash. This form of encryption can not be reversed, but a hacker can encrypt a password and compare it to the compromised encrypted passwords.
According to LinkedIn blog (http://blog.linkedin.com/), the following steps were taken to protect affected members:
Compromised LinkIn members account password have been reset and they will receive an e-mail message with instructions about changing their password.
If you are a LinkedIn member, it is recommended that you change your password immediately.