According to a post on Sophos, Comcast has reset the passwords on 200,000 customers after a security researcher discovered an advertisement on the Dark Web offering to sell 500,000 Comcast passwords in pain text for $1000 in BitCoin. Investigation by Comcast found that “only” 200,000 of there accounts were active and proactively reset the passwords on all the affected accounts. Comcast also said that they were not breached directly, but the this list of accounts was acquired a different way.
If you have a Comcast account, you might want to change your password even if you weren’t one of the subscribers who were reset automatically.
More info: SophosShare