From 8b5c2192e8698f777102cf56bdbed2170df09cc0 Mon Sep 17 00:00:00 2001
From: Adrian Holovaty <adrian@holovaty.com>
Date: Thu, 29 Dec 2005 20:33:56 +0000
Subject: [PATCH] Fixed #1135 -- Changed django.core.mail functions not to
allow newlines in headers
git-svn-id: http://code.djangoproject.com/svn/django/trunk@1795 bcc190cf-cafb-0310-a4f2-bffc1f526a37
---
django/core/mail.py | 9 ++++++++-
docs/email.txt | 38 ++++++++++++++++++++++++++++++++++++++
2 files changed, 46 insertions(+), 1 deletion(-)
diff --git a/django/core/mail.py b/django/core/mail.py
index 24a85d77f0..07c2e666e3 100644
--- a/django/core/mail.py
+++ b/django/core/mail.py
@@ -4,6 +4,13 @@ from django.conf.settings import DEFAULT_FROM_EMAIL, EMAIL_HOST, EMAIL_SUBJECT_P
from email.MIMEText import MIMEText
import smtplib
+class SafeMIMEText(MIMEText):
+ def __setitem__(self, name, val):
+ "Forbids multi-line headers, to prevent header injection."
+ if '\n' in val or '\r' in val:
+ raise ValueError, "Header values can't contain newlines (got %r for header %r)" % (val, name)
+ MIMEText.__setitem__(self, name, val)
+
def send_mail(subject, message, from_email, recipient_list, fail_silently=False):
"""
Easy wrapper for sending a single message to a recipient list. All members
@@ -29,7 +36,7 @@ def send_mass_mail(datatuple, fail_silently=False):
if not recipient_list:
continue
from_email = from_email or DEFAULT_FROM_EMAIL
- msg = MIMEText(message)
+ msg = SafeMIMEText(message)
msg['Subject'] = subject
msg['From'] = from_email
msg['To'] = ', '.join(recipient_list)
diff --git a/docs/email.txt b/docs/email.txt
index b7450b8a14..f07062df36 100644
--- a/docs/email.txt
+++ b/docs/email.txt
@@ -114,3 +114,41 @@ receiving a separate e-mail::
('Subject', 'Message.', 'from@example.com', ['jane@example.com'],
)
send_mass_mail(datatuple)
+
+Preventing header injection
+===========================
+
+**New in Django development version.**
+
+`Header injection`_ is a security exploit in which an attacker inserts extra
+e-mail headers to control the "To:" and "From:" in e-mail messages that your
+scripts generate.
+
+The Django e-mail functions outlined above all protect against header injection
+by forbidding newlines in header values. If any ``subject``, ``from_email`` or
+``recipient_list`` contains a newline, the e-mail function (e.g.
+``send_mail()``) will raise ``ValueError`` and, hence, will not send the
+e-mail. It's your responsibility to validate all data before passing it to the
+e-mail functions.
+
+Here's an example view that takes a ``subject``, ``message`` and ``from_email``
+from the request's POST data, sends that to admin@example.com and redirects to
+"/contact/thanks/" when it's done::
+
+ from django.core.mail import send_mail
+
+ def send_email(request):
+ subject = request.POST.get('subject', '')
+ message = request.POST.get('message', '')
+ from_email = request.POST.get('from_email', '')
+ if subject and message and from_email \
+ and '\n' not in subject and '\n' not in message
+ and '\n' not in from_email:
+ send_mail(subject, message, from_email, ['admin@example.com'])
+ return HttpResponseRedirect('/contact/thanks/')
+ else:
+ # In reality we'd use a manipulator
+ # to get proper validation errors.
+ return HttpResponse('Make sure all fields are entered and valid.')
+
+.. _Header injection: http://securephp.damonkohler.com/index.php/Email_Injection