On Python 3.9.5+, URLValidator didn't prohibit newlines and tabs. If you used values with newlines in HTTP response, you could suffer from header injection attacks. Django itself wasn't vulnerable because HttpResponse prohibits newlines in HTTP headers. Moreover, the URLField form field which uses URLValidator silently removes newlines and tabs on Python 3.9.5+, so the possibility of newlines entering your data only existed if you are using this validator outside of the form fields. The issue is fixed in Django version 3.2.2.
On Python 3.9.5+, URLValidator didn't prohibit newlines and tabs. If you used values with newlines in HTTP response, you could suffer from header injection attacks. Django itself wasn't vulnerable because HttpResponse prohibits newlines in HTTP headers. Moreover, the URLField form field which uses URLValidator silently removes newlines and tabs on Python 3.9.5+, so the possibility of newlines entering your data only existed if you are using this validator outside of the form fields. The issue is fixed in Django version 3.2.2.
https://www.djangoproject.com/weblog/2021/may/06/security-releases/ https://github.com/django/django/commit/2d2c1d0c97832860fbd6597977e2aae17dd7e5b2
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