DjangoCRM: Unauthenticated Open Redirect via toggle_default_sorting next_url Parameter

DjangoCRM's toggle_default_sorting view is the only route in common/urls.py that is not wrapped in login_required or staff_member_required, and it redirects to a caller-supplied next_url GET parameter after only checking secure_url(next_url), which merely verifies the target host matches the current site's domain (blocking only cross-domain redirects) while allowing any same-site path with no authentication required to reach the view. This enables unauthenticated phishing redirects and referrer-based token leakage via redirect chains.