Firefox session cookies

user_63751 0
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Generally speaking, when given a cookie that has no expiration period, modern browsers will consider this cookie to be a 'session cookie', they will remove the cookie at the end of the browsing session (generally when the browser instance closes).

IE, Opera, Safari and Chrome all support this behavior.

However firefox (3.0.9 latest proper release) appears not to follow this rule, from what I can tell it doesn't expire the cookies when the browser is closed, or when the user logs off or restarts the OS..

So, why does firefox refer to these as session cookies, when they last aparently indefinitely?

Does anyone know how Firefox handles session cookie expiration?

firefox session cookies
8 Answers

This is apparently by design. Check out this Bugzilla bug: https://bugzilla.mozilla.org/show_bug.cgi?id=443354

Firefox has a feature where you close Firefox and it offers to save all your tabs, and then you restore the browser and those tabs come back. That's called session restore. What I didn't realize is that it'll also restore all the session cookies for those pages too! It treats it like you had never closed the browser.

This makes sense in the sense that if your browser crashed you get right back to where you were, but is a little disconcerting for web devs used to session cookies getting cleared. I've got some old session cookies from months ago that were set by sites I always have open in tabs.

To test this out, close all the tabs in your browser, then close the browser and restart it. I think the session cookies for your site should clear in that case. Otherwise you'd have to turn off session restore.

user_112840
user_3830290

This should work. I used to be one of the cookie module testers, and I don't think there is any design reason this would behave differently (although if you crash, the session cookies might be designed to live on when you restart...)

Are you viewing the cookies in the "Preferences" menu > "Privacy" Tab > "Show Cookies..." button?

Also, have you tried a new profile?

benc_29100

This is a bit of a concern in shared user environments. If I set a authentication cookie that is set to expire at the end of the session. This will persist in Firefox after the browser has been closed and another user starts up Firefox. Cookies are set with an expiry date for a reason!

user_13022950

In my case, it was because of pinned tabs that automatically restored the session even if this option was disabled in Firefox settings. So if you unpin the tabs, the session won't be restored.

user_142217870
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