Android Forums and Nvidia's forums are added the to list of web sites hacked in the last few days. After closing its forums last week citing a "system issue," Nvidia said that the issue was a large-scale attack by an unknown hacker. Nvidia says its investigation has revealed the hacker gained access to user information including usernames, email addresses, hashed and salted passwords. According to Nvidia, Nvidia Forums, Nvidia Developers Zone, and the Nvidia Research site were hacked.

Although Nvidia hashed all the passwords with a random salt value, making them more secure, the company recommends you change your password elsewhere if you used an identical one. The company will send all Nvidia users a temporary password when the service comes back online, along with instructions on how to change it.

In related news, AndroidForums.com, an online forum for Android users, was also the target of a hacker attack, its operator Phandroid.com said on Thursday.

Members of Android Forums have been asked to change their passwords ever since Tuesday, after it was found that the server hosting the forum was compromised and the website's database was accessed. The forum has over 1 million users.

"The user table of AndroidForum's database was accessed," an Android Forums Community Manager, called Phases, said in a post on the website on Tuesday. He said it was completely possible that data was downloaded, and the forum has taken action assuming that it was.

Information in the user database included information such as unique IDs, usernames, emails, hashed and 'salted" passwords, and registration IP addresses, according to the post.

Users have been advised to change their password on Android Forums and other sites where they may use the same username and password.

Hackers published on the Internet on Thursday a list of over 453,000 log-in credentials that were allegedly stolen from a database associated with a Yahoo service.