Update 2: Steam is now online once more with all services resumed. Valve have issued this statement to Gamespot:
"Steam is back up and running without any known issues. As a result of a configuration change earlier today, a caching issue allowed some users to randomly see pages generated for other users for a period of less than an hour. This issue has since been resolved. We believe no unauthorized actions were allowed on accounts beyond the viewing of cached page information and no additional action is required by users."
Config change on Christmas Day? Those folks do work hard. If you see any abnormalities with your account - and there really shouldn't be any, but hey, who knows - Steam support is your best option. Remember that it is, well, you know, a holiday period, so replies may be even slower than normal.
Sure hope the best games of 2015 are on GOG.
Update: Steam is now offline. The closest we have to an official statement is this post from a Steam Community Moderator. Valve is working on it and your particularly sensitive information has not been compromised.
If my reading of the situation is correct, the chance that you have been affected is incredibly low, and possibly zero if you haven't been on your account details page recently. Here's what might have been exposed if you were:
- Account name and associated e-mail
- Last two digits of card numbers or entire Paypal e-mail address
- Wallet balance, purchase history and games owned
- Home address registered for purchases
- Steam Guard status
With all the servers down there's probably not a lot you can do about this right now except change passwords on anything that uses the same address, just in case. As I mentioned before, as far as I could tell it was impossible for someone to actually change anything on your account as they weren't actually logged in and attempting to do so produced an error message. It is not the end times, but it was shaky for a little bit there.
Original Story: I kept joking about what we should do news-wise if Half-Life 3 was announced over the Christmas break. This is a little less exciting. Something's gone terribly wrong over at Steam HQ, where what's been surmised as a caching problem is delivering random account details pages to users. Individuals are able to access limited financial information - just the final couple of digits of cards and full PayPal e-mail addresses - but can see purchase history, login names, signup addresses and other information.
If you're hoping for a solution, there doesn't seem to be one right now. Not going anywhere near Steam is your best bet, either via the web page or the desktop client. From my limited understanding of caching, the only thing that's likely to do is expose your information to other people, as you will be put into the system that's currently randomly assigning Jim from Tennessee to Jenny from Helsinki.
The good news is it seems to be impossible to make purchases or otherwise change information on someone's account. Due to the nature of the problem, you aren't actually logged in using that person's details, you're just getting to see a page you're not meant to. This is why the account you're seeing changes every time you switch page.
For now, it looks like Valve are taking the Steam servers offline. Hellish timing for them. We'll update if and when they give the all clear.