An anonymous reader writes "Altinn.no is a web service run by the Norwegian government, on which citizens can find, fill out and deliver forms electronically. Every year Norwegian citizens can also log in to check their tax results. This year, as every year, the site was unable to cope with the traffic generated from everyone wanting to check their taxes at the same time. New this year, however, was that once people were finally able to log in, a significant amount of people were logged in as someone else. Users then had access to all financial data of this unfortunate person over two years back in time, in addition to the financial information of his wife and the company he worked for. Altinn shut down some 15 minutes later, and has been down since."