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

1 files changed, 17 insertions, 2 deletions

diff --git a/docs/releases/3.2.2.txt b/docs/releases/3.2.2.txt
index d47da08d6c..a899bc6e29 100644
--- a/docs/releases/3.2.2.txt
+++ b/docs/releases/3.2.2.txt
@@ -2,9 +2,24 @@
 Django 3.2.2 release notes
 ==========================
 
-*Expected June 1, 2021*
+*May 6, 2021*
 
-Django 3.2.2 fixes several bugs in 3.2.1.
+Django 3.2.2 fixes a security issue and a bug in 3.2.1.
+
+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.
 
 Bugfixes
 ========