[4.2.x] Fixed CVE-2023-46695 -- Fixed potential DoS in UsernameField on Windows.

Thanks MProgrammer (https://hackerone.com/mprogrammer) for the report.

1 files changed, 7 insertions, 0 deletions

diff --git a/tests/auth_tests/test_forms.py b/tests/auth_tests/test_forms.py
index 7a80adbf31..81c56a428e 100644
--- a/tests/auth_tests/test_forms.py
+++ b/tests/auth_tests/test_forms.py
@@ -14,6 +14,7 @@ from django.contrib.auth.forms import (
     SetPasswordForm,
     UserChangeForm,
     UserCreationForm,
+    UsernameField,
 )
 from django.contrib.auth.models import User
 from django.contrib.auth.signals import user_login_failed
@@ -154,6 +155,12 @@ class BaseUserCreationFormTest(TestDataMixin, TestCase):
         self.assertNotEqual(user.username, ohm_username)
         self.assertEqual(user.username, "testΩ")  # U+03A9 GREEK CAPITAL LETTER OMEGA
 
+    def test_invalid_username_no_normalize(self):
+        field = UsernameField(max_length=254)
+        # Usernames are not normalized if they are too long.
+        self.assertEqual(field.to_python("½" * 255), "½" * 255)
+        self.assertEqual(field.to_python("ff" * 254), "ff" * 254)
+
     def test_duplicate_normalized_unicode(self):
         """
         To prevent almost identical usernames, visually identical but differing