From 96edab777ae3820c322bbcf6e5c1d2c7867cb477 Mon Sep 17 00:00:00 2001
From: Kliment Lamonov <klimentlamonov@yandex.ru>
Date: Sat, 12 Jul 2025 16:30:09 +0300
Subject: [PATCH] gh-134759: fix `UnboundLocalError` in
 `email.message.Message.get_payload` (GH-136071) (cherry picked from commit
 25335d297b5248922a4c82183bcdf0c0ada8352b)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Kliment Lamonov <klimentlamonov@yandex.ru>
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
---
 Lib/email/message.py                                     | 2 ++
 Lib/test/test_email/test_message.py                      | 9 +++++++++
 Misc/ACKS                                                | 1 +
 .../2025-06-28-11-32-57.gh-issue-134759.AjjKcG.rst       | 2 ++
 4 files changed, 14 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2025-06-28-11-32-57.gh-issue-134759.AjjKcG.rst

diff --git a/Lib/email/message.py b/Lib/email/message.py
index f48fcd2ea925da..37771f97b0c8a6 100644
--- a/Lib/email/message.py
+++ b/Lib/email/message.py
@@ -313,6 +313,8 @@ def get_payload(self, i=None, decode=False):
                 # If it does happen, turn the string into bytes in a way
                 # guaranteed not to fail.
                 bpayload = payload.encode('raw-unicode-escape')
+        else:
+            bpayload = payload
         if cte == 'quoted-printable':
             return quopri.decodestring(bpayload)
         elif cte == 'base64':
diff --git a/Lib/test/test_email/test_message.py b/Lib/test/test_email/test_message.py
index 96979db27f3a21..411524fef66252 100644
--- a/Lib/test/test_email/test_message.py
+++ b/Lib/test/test_email/test_message.py
@@ -1031,6 +1031,15 @@ def test_get_body_malformed(self):
         # AttributeError: 'str' object has no attribute 'is_attachment'
         m.get_body()
 
+    def test_get_bytes_payload_with_quoted_printable_encoding(self):
+        # We use a memoryview to avoid directly changing the private payload
+        # and to prevent using the dedicated paths for string or bytes objects.
+        payload = memoryview(b'Some payload')
+        m = self._make_message()
+        m.add_header('Content-Transfer-Encoding', 'quoted-printable')
+        m.set_payload(payload)
+        self.assertEqual(m.get_payload(decode=True), payload)
+
 
 class TestMIMEPart(TestEmailMessageBase, TestEmailBase):
     # Doing the full test run here may seem a bit redundant, since the two
diff --git a/Misc/ACKS b/Misc/ACKS
index d0aaf75ebcc1f7..6cc30812cced11 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1040,6 +1040,7 @@ Alexander Lakeev
 David Lam
 Thomas Lamb
 Valerie Lambert
+Kliment Lamonov
 Peter Lamut
 Jean-Baptiste "Jiba" Lamy
 Ronan Lamy
diff --git a/Misc/NEWS.d/next/Library/2025-06-28-11-32-57.gh-issue-134759.AjjKcG.rst b/Misc/NEWS.d/next/Library/2025-06-28-11-32-57.gh-issue-134759.AjjKcG.rst
new file mode 100644
index 00000000000000..79b85320926954
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-06-28-11-32-57.gh-issue-134759.AjjKcG.rst
@@ -0,0 +1,2 @@
+Fix :exc:`UnboundLocalError` in :func:`email.message.Message.get_payload` when
+the payload to decode is a :class:`bytes` object. Patch by Kliment Lamonov.