In Django 1.11.x before 1.11.18, 2.0.x before 2.0.10, and 2.1.x before 2.1.5, an Improper Neutralization of Special Elements in Output Used by a Downstream Component issue exists in django.views.defaults.page_not_found(), leading to content spoofing (in a 404 error page) if a user fails to recognize that a crafted URL has malicious content.