According to Twitch, “We are writing to let you know that there may have been unauthorized access to some Twitch user account information. For your protection, we have expired passwords and stream keys and have disconnected accounts from Twitter and YouTube. As a result, you will be prompted to create a new password the next time you attempt to log into your Twitch account.”
In addition to that, the website has also disconnected all accounts from both Twitter and YouTube. Does it seem a bit extreme? We suppose it does, but at the same time we guess we can’t blame the folks at Twitch for being extra cautious. Unfortunately Twitch does not mention if user information like credit card details might have been compromised, but users who have been affected are expected to hear from Twitch very soon. In the meantime you should probably go ahead and change your passwords just to be safe.