Ensure EmailAddress can't contain newlines

anymail/utils.py

@@ -212,6 +212,14 @@ class EmailAddress:
                 display_name, addr_spec = display_name  # unpack (name,addr) tuple
             except ValueError:
                 pass
+
+        # ESPs should clean or reject addresses containing newlines, but some
+        # extra protection can't hurt (and it seems to be a common oversight)
+        if '\n' in display_name or '\r' in display_name:
+            raise ValueError('EmailAddress display_name cannot contain newlines')
+        if '\n' in addr_spec or '\r' in addr_spec:
+            raise ValueError('EmailAddress addr_spec cannot contain newlines')
+
         self.display_name = display_name
         self.addr_spec = addr_spec
         try:

tests/test_utils.py

@@ -159,6 +159,19 @@ class ParseAddressListTests(SimpleTestCase):
         with self.assertRaisesMessage(AnymailInvalidAddress, "Invalid email address"):
             parse_single_address(" ")
 
+    def test_no_newlines(self):
+        # (Parsing shouldn't even be able to even generate these cases,
+        # but in case anyone constructs an EmailAddress directly...)
+        for name, addr in [
+            ("Potential\nInjection", "addr@example.com"),
+            ("Potential\rInjection", "addr@example.com"),
+            ("Name", "potential\ninjection@example.com"),
+            ("Name", "potential\rinjection@example.com"),
+        ]:
+            with self.subTest(name=name, addr=addr):
+                with self.assertRaisesMessage(ValueError, "cannot contain newlines"):
+                    _ = EmailAddress(name, addr)
+
 
 class NormalizedAttachmentTests(SimpleTestCase):
     """Test utils.Attachment"""