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The view_survey endpoint accepted a redirect_url GET parameter and passed
it directly to HttpResponseRedirect() with no validation. If a non-existent
survey name was requested, this produced an immediate 302 to an
attacker-controlled URL. If a valid survey was requested, the same URL was
embedded in a hidden _redirect_url form field; after submission, submit_answers
echoed it back in JSON and client-side JS used it as location.href — a second
unvalidated redirect path.
Fix both by ignoring user-supplied redirect URLs entirely:
- view_survey no longer reads redirect_url from GET params
- submit_answers always redirects to reverse('dashboard') rather than
reading _redirect_url from the POST body
Note: view_student_survey retains its redirect_url parameter because it is
also called from the courseware view (courseware/views/views.py), which passes
a server-controlled course_home_url. That call path is unaffected.
Fixes: GHSA-2843-x998-f8r2
BREAKING CHANGE: The redirect_url GET parameter on /survey/<name>/ is no longer
honored. Requests that previously redirected to a caller-specified URL after
survey completion will now always redirect to the dashboard.
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Merging via approval from https://github.com/openedx/openedx-platform-ghsa-2843-x998-f8r2/pull/1 |
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The view_survey endpoint accepted a redirect_url GET parameter and passed
it directly to HttpResponseRedirect() with no validation. If a non-existent
survey name was requested, this produced an immediate 302 to an
attacker-controlled URL. If a valid survey was requested, the same URL was
embedded in a hidden _redirect_url form field; after submission, submit_answers
echoed it back in JSON and client-side JS used it as location.href — a second
unvalidated redirect path.
Fix both by ignoring user-supplied redirect URLs entirely:
reading _redirect_url from the POST body
Note: view_student_survey retains its redirect_url parameter because it is
also called from the courseware view (courseware/views/views.py), which passes
a server-controlled course_home_url. That call path is unaffected.
Fixes: GHSA-2843-x998-f8r2
BREAKING CHANGE: The redirect_url GET parameter on /survey// is no longer
honored. Requests that previously redirected to a caller-specified URL after
survey completion will now always redirect to the dashboard.