django/docs/releases/2.2.22.txt

===========================
Django 2.2.22 release notes
===========================

*May 6, 2021*

Django 2.2.22 fixes a security issue in 2.2.21.

CVE-2021-32052: Header injection possibility since ``URLValidator`` accepted newlines in input on Python 3.9.5+
===============================================================================================================

On Python 3.9.5+, :class:`~django.core.validators.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
:class:`~django.http.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.

This issue was introduced by the :bpo:`43882` fix.
Fixed #32713, Fixed CVE-2021-32052 -- Prevented newlines and tabs from being accepted in URLValidator on Python 3.9.5+. In Python 3.9.5+ urllib.parse() automatically removes ASCII newlines and tabs from URLs [1, 2]. Unfortunately it created an issue in the URLValidator. URLValidator uses urllib.urlsplit() and urllib.urlunsplit() for creating a URL variant with Punycode which no longer contains newlines and tabs in Python 3.9.5+. As a consequence, the regular expression matched the URL (without unsafe characters) and the source value (with unsafe characters) was considered valid. [1] https://bugs.python.org/issue43882 and [2] https://github.com/python/cpython/commit/76cd81d60310d65d01f9d7b48a8985d8ab89c8b4 2021-05-06 06:45:23 +00:00			`===========================`
			`Django 2.2.22 release notes`
			`===========================`

			`May 6, 2021`

			`Django 2.2.22 fixes a security issue in 2.2.21.`

			CVE-2021-32052: Header injection possibility since ``URLValidator`` accepted newlines in input on Python 3.9.5+
			`===============================================================================================================`

			On Python 3.9.5+, :class:`~django.core.validators.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`
			:class:`~django.http.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.`

			This issue was introduced by the :bpo:`43882` fix.