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Fixed #6941 -- When logging a user out, or when logging in with an e…


session and a different user id to the current session owner, flush the session
data to avoid leakage. Logging in and moving from an anonymous user to a
validated user still keeps existing session data.

Backwards incompatible if you were assuming sessions persisted past logout.

git-svn-id: bcc190cf-cafb-0310-a4f2-bffc1f526a37
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malcolmt committed Aug 14, 2008
1 parent 5e8efa9 commit 97a7dab2b19b87652bc15c5db4cb06cd7011fe4d
Showing with 21 additions and 11 deletions.
  1. +7 −9 django/contrib/auth/
  2. +7 −0 docs/authentication.txt
  3. +7 −2 docs/sessions.txt
@@ -53,23 +53,21 @@ def login(request, user):
# TODO: It would be nice to support different login methods, like signed cookies.
user.last_login =
+ if request.session.get('SESSION_KEY', !=
+ # To avoid reusing another user's session, create a new, empty session
+ # if the existing session corresponds to a different authenticated user.
+ request.session.flush()
request.session[SESSION_KEY] =
request.session[BACKEND_SESSION_KEY] = user.backend
if hasattr(request, 'user'):
request.user = user
def logout(request):
- Remove the authenticated user's ID from the request.
+ Removes the authenticated user's ID from the request and flushes their
+ session data.
- try:
- del request.session[SESSION_KEY]
- except KeyError:
- pass
- try:
- del request.session[BACKEND_SESSION_KEY]
- except KeyError:
- pass
+ request.session.flush()
if hasattr(request, 'user'):
from django.contrib.auth.models import AnonymousUser
request.user = AnonymousUser()
@@ -426,6 +426,13 @@ use ``django.contrib.auth.logout()`` within your view. It takes an
Note that ``logout()`` doesn't throw any errors if the user wasn't logged in.
+**New in Django development version:** When you call ``logout()``, the session
+data for the current request is completely cleaned out. All existing data is
+removed. This is to prevent another person from using the same web browser to
+log in and have access to the previous user's session data. If you want to put
+anything into the session that will be available to the user immediately after
+logging out, do that *after* calling ``django.contrib.auth.logout()``.
Limiting access to logged-in users
@@ -117,8 +117,8 @@ It also has these methods:
Delete the current session data from the database and regenerate the
session key value that is sent back to the user in the cookie. This is
used if you want to ensure that the previous session data can't be
- accessed again from the user's browser (for example, the standard
- ``logout()`` method calls it).
+ accessed again from the user's browser (for example, the
+ ``django.contrib.auth.logout()`` method calls it).
* ``set_test_cookie()``
@@ -230,6 +230,11 @@ This simplistic view logs in a "member" of the site::
return HttpResponse("You're logged out.")
+The standard ``django.contrib.auth.logout()`` function actually does a bit
+more than this to prevent inadvertent data leakage. It calls
+``request.session.flush()``. We are using this example as a demonstration of
+how to work with session objects, not as a full ``logout()`` implementation.
Setting test cookies

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