Comcast reset the passwords of approximately 200,000 accounts after learning that almost 600,000 passwords were for sale on the dark net for $1,000, the company told the Washington Post Monday.

Many of the affected accounts are inactive, but those that are still activated are among the 200,000 passwords that were reset.

As a precaution, users are encouraged to change their password as soon as possible.

Comcast denied that it was breached, and said the passwords were likely gained from prior malicious software campaigns, phishing attacks or other third party attacks.

The identity of the person selling the passwords could not be verified.

"We're taking this seriously and we're working to get this fixed for those customers who may have been impacted, but the vast majority of information out there was invalid," a Comcast spokesperson told the Washington Post.