No need to panic. These were not general Yahoo or Flickr passwords stolen. Yahoo bought some company years ago and it is passwords from this company that were not encrypted.
"ďMy guess right now, although itís early in the investigation, is that the 435,000 accounts are pre-Yahoo,Ē he wrote, saying that they may be from Associated Contentís databases before Yahoo bought the company in 2010."
"If you have ever contributed or signed up to contribute to Yahoo Voices or Associated Content, itís well worth changing that password ó and changing your passwords and usernames for any other account with the same log-in information."