From 5b67aca6fb4246e84981d6361ba218bd52e73ac2 Mon Sep 17 00:00:00 2001
From: Tomas Orsava <torsava@redhat.com>
Date: Tue, 21 Jun 2016 15:52:03 +0200
Subject: [PATCH] Raise an error when STARTTLS fails

CVE-2016-0772 python: smtplib StartTLS stripping attack
rhbz#1303647: https://bugzilla.redhat.com/show_bug.cgi?id=1303647

Based on an upstream change by Benjamin Peterson <benjamin@python.org>
- in changeset 101886:b3ce713fb9be 2.7
- https://hg.python.org/cpython/rev/b3ce713fb9be
---
 Lib/smtplib.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Lib/smtplib.py b/Lib/smtplib.py
index dc16ef6..8bc806b 100755
--- a/Lib/smtplib.py
+++ b/Lib/smtplib.py
@@ -655,6 +655,11 @@ class SMTP:
             self.ehlo_resp = None
             self.esmtp_features = {}
             self.does_esmtp = 0
+        else:
+            # RFC 3207:
+            # 501 Syntax error (no parameters allowed)
+            # 454 TLS not available due to temporary reason
+            raise SMTPResponseException(resp, reply)
         return (resp, reply)
 
     def sendmail(self, from_addr, to_addrs, msg, mail_options=[],
-- 
2.5.5