Opened 10 years ago

Closed 10 years ago

#22638 closed Bug (fixed)

Form wizard may raise unreasonable exceptions in case of SECRET_KEY change

Reported by: Sasha Romijn Owned by: Sasha Romijn
Component: contrib.formtools Version: 1.6
Severity: Normal Keywords:
Cc: denis.cornehl@… Triage Stage: Ready for checkin
Has patch: yes Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no


Our form wizard has two storage options: sessions and cookies, with SessionWizardView and CookieWizardView. To prevent manipulation, the cookies storage uses the signed cookies from django.core.signing. This creates a signature based on the SECRET_KEY. If the secret key is changed, request.get_signed_cookie will raise an exception, in which case the storage will raise WizardViewCookieModified, a subclass of SuspiciousOperation.

The cookie is loaded very early in the rendering of a the form wizard view. This means that if a user starts a form wizard, and the secret key is changed, any requests to the wizard will result in an exception and likely a 500 error. The user can only recover from this by deleting the cookie or restarting the browser (it seems to only persist in the current session).

It may appear sensible to raise a SuspiciousOperation for a possible cookie manipulation, but we currently don't do this in any other place, like sessions. Currently, user may suddenly get 500 errors for no clear reason, and the developer of the project has no ability to help them. Leaving this as is may also discourage people from rotating their secret key when needed.

I suggest that in case of an invalid wizard cookie, we simply ignore the value and thereby return the user to the first step.

Change History (11)

comment:1 by Tim Graham, 10 years ago

Triage Stage: UnreviewedAccepted

comment:2 by nott, 10 years ago

WizardViewCookieModified, a subclass of SuspiciousOperation, is raised in this situation since 1.6

comment:3 by nott, 10 years ago

Owner: changed from nobody to nott
Status: newassigned

comment:4 by Sasha Romijn, 10 years ago

Has patch: set

Apologies, forgot to assign this to myself before working on it. Wrote a PR on

comment:5 by Sasha Romijn, 10 years ago

Owner: nott removed
Status: assignednew

comment:6 by Denis Cornehl, 10 years ago

tested the behavior with a test-application, looks fine to me.

comment:7 by Denis Cornehl, 10 years ago

Cc: denis.cornehl@… added
Patch needs improvement: set

comment:8 by Sasha Romijn, 10 years ago

Patch needs improvement: unset

comment:9 by Claude Paroz, 10 years ago

Triage Stage: AcceptedReady for checkin

comment:10 by Sasha Romijn, 10 years ago

Owner: set to Sasha Romijn
Status: newassigned

comment:11 by Erik Romijn <eromijn@…>, 10 years ago

Resolution: fixed
Status: assignedclosed

In ba5ddf7aed542d25f0fdb25a04d87305de0f3972:

Fixed #22638 -- Changed CookieWizardView to ignore invalid cookies

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