[3.2.x] Fixed CVE-2022-41323 -- Prevented locales being interpreted as regular expressions.

adamchainz · carltongibson · commit 5b6b257fa7ec · 2022-09-27T10:17:34.000+02:00
Thanks to Benjamin Balder Bach for the report.
diff --git a/django/urls/resolvers.py b/django/urls/resolvers.py
@@ -303,7 +303,7 @@ def __init__(self, prefix_default_language=True):
     @property
     def regex(self):
         # This is only used by reverse() and cached in _reverse_dict.
-        return re.compile(self.language_prefix)
+        return re.compile(re.escape(self.language_prefix))
 
     @property
     def language_prefix(self):
diff --git a/docs/releases/3.2.16.txt b/docs/releases/3.2.16.txt
@@ -6,4 +6,8 @@ Django 3.2.16 release notes
 
 Django 3.2.16 fixes a security issue with severity "medium" in 3.2.15.
 
-...
+CVE-2022-41323: Potential denial-of-service vulnerability in internationalized URLs
+===================================================================================
+
+Internationalized URLs were subject to potential denial of service attack via
+the locale parameter.
diff --git a/tests/i18n/patterns/tests.py b/tests/i18n/patterns/tests.py
@@ -172,6 +172,12 @@ def test_translate_url_utility(self):
             self.assertEqual(translate_url('/nl/gebruikers/', 'en'), '/en/users/')
             self.assertEqual(translation.get_language(), 'nl')
 
+    def test_locale_not_interepreted_as_regex(self):
+        with translation.override("e("):
+            # Would previously error:
+            # re.error: missing ), unterminated subpattern at position 1
+            reverse("users")
+
 
 class URLNamespaceTests(URLTestCaseBase):
     """
