1053875 - Private Browsing is not really private between 2 private windows

Status: RESOLVED DUPLICATE of bug 117222

(Firefox :: Private Browsing, defect)

Description

[Manuel Kaufmann]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:31.0) Gecko/20100101 Firefox/31.0 (Beta/Release)
Build ID: 20140715214327

Steps to reproduce:

There are the steps to reproduce the issue:

1. Start Firefox
2. Open a Private Window
3. Go to http://twitter.com
4. Sign in
5. Open another Private Window
6. Go to http://twitter.com



Actual results:

As result:

7. You are already Signed in in the Recently opened Private Window

The other way around also reproduce this bug. You can Sign in in the second Private Window, then close it, and go to http://twitter.com with the first one open and you are still logged in in that page.


Expected results:

I expected to be logged out in the new Private Window. It seems that the information is shared between all the Private Windows which is dangerous because it's not really a Private Browsing as it says.

Comment 1

[Benjamin Smedberg]

Ehsan this is by design, right?

Comment 2

[(no longer active)]

Yes.

Comment 3

[Manuel Kaufmann]

What does it mean? It's confusing for the final user. At least, it should be alert about that, or limited to just open ONE Private Window. Don't you think?

Comment 4

[Curtis Koenig [:curtisk-use curtis.koenig+bzATgmail.com]]]

The limitations and abilities of Private Browsing are fairly well documented, you may want to review the following information:

https://support.mozilla.org/en-US/kb/private-browsing-browse-web-without-saving-info?redirectlocale=en-US&redirectslug=Private+Browsing

http://www.ghacks.net/2013/05/07/limit-firefoxs-private-browsing-mode-to-one-window-and-add-other-options-to-it/

Comment 5

[(no longer active)]

(In reply to Manuel Kaufmann from comment #3)
> What does it mean? It's confusing for the final user. At least, it should be
> alert about that, or limited to just open ONE Private Window. Don't you
> think?

It means that your private windows and tabs are separated from your non-private ones, and they don't store any traces from your browsing activity.  Private Browsing is *not* guest mode.

Comment 6

[Gina Smith]

This should NOT be labeled as resolved nor invalid.  As it is, Private Browsing is a hack that isolates a second session.  It should be that each individual private window gets its own session.

Let's put this another way:  As a web developer, I recently discovered this problem with private browsing as I was testing Facebook support for a website.  I wanted to sign into two distinct Facebook accounts and have a third window where I wasn't signed in at all.  In Firefox, this is impossible.  Multiple session isolation across windows is a very real and desirable scenario.  Also, the entire plugin and extension infrastructure needs to be adjusted to properly support session isolation.

The user assumes that each private window gets its own brand new session.  The reality is that they do not.  At the very least, if the user opens two distinct private windows in the same Firefox instance, they should be alerted to the limitations of private browsing.

To label this bug as RESOLVED INVALID is typical behavior of the Firefox development community.  It needs to be part of a package update that fixes the broken nature of Private Browsing as a whole.