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

Thanks to Benjamin Balder Bach for the report.

django/urls/resolvers.py

@@ -338,7 +338,7 @@ class LocalePrefixPattern:
     @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):

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.

docs/releases/4.0.8.txt

@@ -6,4 +6,8 @@ Django 4.0.8 release notes
 
 Django 4.0.8 fixes a security issue with severity "medium" in 4.0.7.
 
-...
+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.

tests/i18n/patterns/tests.py

@@ -198,6 +198,12 @@ class URLTranslationTests(URLTestCaseBase):
             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):
     """