Logged as someone else ; Valve's cache issue

[Kuma]

https://www.reddit.com/r/Steam/comments/3y7le9/im_logged_in_as_someone_random_on_steam/

 

 

https://www.reddit.com/r/Steam/comments/3y7r0b/do_not_login_to_any_steam_websites/

 

 

 

 

It goes without saying, but avoid logging into any Steam websites until the security issue has been remedied.

If you know you're already logged in, do NOT visit any Steam Community or Steam Store URL. This includes any internet browsers and the Steam Desktop/Mobile Client!

Playing games online should be fine. It'll also prevent anybody else from logging into your account via desktop client.

Explanation according to Steam DB:

Valve is having caching issues, allowing users to view things such as account information of other users.

This is also why the Steam website has been displaying in different languages.