LinkedIn has confirmed that 6 million account passwords were hacked. Linkedin has confirmed on their blog that Member Passwords have been compromised and should be reset.
Many Linkedin members have been receiving fake notices like the one below telling them to confirm their email address however the link takes unsuspecting recipients to a site selling counterfeit drugs.

On June 6, it was revealed that 6.4 million passwords from LinkedIn had been posted on a Russian web forum, along with a message encouraging other hackers to help decrypt the “hashed” data.
Please reset your password on your Linkedin immediately as well it is recommended that you should change your email and other social media passwords to a more complex 12 character password
