We use TFS 2013 on premise. I just noticed a weird issue with the web interface, namely I can properly sign out only from Firefox.
When I use Chrome, IE or Opera, hitting the "sign out" link shows the proper signout page, saying:
Sign out: close browser to complete sign out
You must close your browser to complete the sign out process.
But after I open a new instance and hit http://servername:8080/tfs - hoping to see the "Authentication required" popup - the welcome page loads as if I had logged in already.
I erased all browsing history, temporary files, cookies and website data, form data, saved passwords, etc. for all browsers, checked Microsoft Credential Manager in case it has a TFS related entry, I rebooted the PC, but no result.
The installed browsers:
Firefox 36.0
Chrome 40.0.2214.115 m
IE 11.0.9600.17633
Opera 27.0.1689.76