Due to a lot of security problems on Christmas Day, the Steam website was down and users were unable to use its service. On Christmas Day (December 25), a lot of users reported they had access to their account, but it was shown wrong details and personal information.
After that, Steam website was shut down for fixing those errors and it’s now online again. According to an official statement from the company, it’s a caching problem, which allowed users to see pages of other users.
The company also confirmed the caching issues have been resolved. Those issues are only caching problems and there is no unauthorized actions were happening to accounts.