Marketers woke this morning to the news that their LinkedIn accounts may have been affected by password hacking, which reportedly affected almost 6.5 million accounts.

A user in a Russian internet forum reportedly publicised his theft of 6,458,020 hashed passwords of members of the professional social network, but was not able to uncover any usernames.

LinkedIn confirmed that the passwords were indeed stolen, posting the following notice on its blog:

“We want to provide you with an update on this morning’s reports of stolen passwords. We can confirm that some of the passwords that were compromised correspond to LinkedIn accounts. We are continuing to investigate this situation and here is what we are pursuing as far as next steps for the compromised accounts:

1. Members that have accounts associated with the compromised passwords will notice that their LinkedIn account password is no longer valid.

2. These members will also receive an email from LinkedIn with instructions on how to reset their passwords. There will not be any links in these emails. For security reasons, you should never change your password on any website by following a link in an email.

3. These affected members will receive a second email from our Customer Support team providing a bit more context on this situation and why they are being asked to change their passwords.

It is worth noting that the affected members who update their passwords and members whose passwords have not been compromised benefit from the enhanced security we just recently put in place, which includes hashing and salting of our current password databases. We sincerely apologize for the inconvenience this has caused our members. We take the security of our members very seriously, if you haven’t read it already it is worth checking out my earlier blog post today about updating your password other account security best practices.”