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cherry-pick from openedx#38274 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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cherry-pick from openedx#38274
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:
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.