Clicking “Account Info” resulted in information being displayed user information belonging to someone else, like email addresses, buying history, and other information that would be otherwise considered private. For those wondering if this is a security breach of sorts or if Steam had been hacked, you can rest assured that they have not.
In fact Valve has since released a statement to comment on the matter. According to Valve, “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.”
While Valve seems to be pretty certain that there has not been any unauthorized activities conducted during that brief window, we suppose if you want to be safe maybe considering upping your Steam account’s security, such as Steam Guard and the mobile app, might be a good idea.