[1.4.x] Prevented newlines from being accepted in some validators.

This is a security fix; disclosure to follow shortly.

Thanks to Sjoerd Job Postmus for the report and draft patch.

django/core/validators.py

@@ -50,7 +50,7 @@ class URLValidator(RegexValidator):
         r'localhost|' #localhost...
         r'\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})' # ...or ip
         r'(?::\d+)?' # optional port
-        r'(?:/?|[/?]\S+)$', re.IGNORECASE)
+        r'(?:/?|[/?]\S+)\Z', re.IGNORECASE)
 
     def __init__(self, verify_exists=False,
                  validator_user_agent=URL_VALIDATOR_USER_AGENT):
@@ -133,11 +133,16 @@ class URLValidator(RegexValidator):
                 raise broken_error
 
 
+integer_validator = RegexValidator(
+    re.compile('^-?\d+\Z'),
+    message=_('Enter a valid integer.'),
+    code='invalid',
+)
+
+
 def validate_integer(value):
-    try:
+    return integer_validator(value)
-        int(value)
+
-    except (ValueError, TypeError):
-        raise ValidationError('')
 
 class EmailValidator(RegexValidator):
 
@@ -160,14 +165,14 @@ email_re = re.compile(
     r"(^[-!#$%&'*+/=?^_`{}|~0-9A-Z]+(\.[-!#$%&'*+/=?^_`{}|~0-9A-Z]+)*"  # dot-atom
     # quoted-string, see also http://tools.ietf.org/html/rfc2822#section-3.2.5
     r'|^"([\001-\010\013\014\016-\037!#-\[\]-\177]|\\[\001-\011\013\014\016-\177])*"'
-    r')@((?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+[A-Z]{2,6}\.?$)'  # domain
+    r')@((?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+[A-Z]{2,6}\.?\Z)'  # domain
-    r'|\[(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\]$', re.IGNORECASE)  # literal form, ipv4 address (SMTP 4.1.3)
+    r'|\[(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\]\Z', re.IGNORECASE)  # literal form, ipv4 address (SMTP 4.1.3)
 validate_email = EmailValidator(email_re, _(u'Enter a valid e-mail address.'), 'invalid')
 
-slug_re = re.compile(r'^[-\w]+$')
+slug_re = re.compile(r'^[-\w]+\Z')
 validate_slug = RegexValidator(slug_re, _(u"Enter a valid 'slug' consisting of letters, numbers, underscores or hyphens."), 'invalid')
 
-ipv4_re = re.compile(r'^(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}$')
+ipv4_re = re.compile(r'^(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\Z')
 validate_ipv4_address = RegexValidator(ipv4_re, _(u'Enter a valid IPv4 address.'), 'invalid')
 
 def validate_ipv6_address(value):
@@ -205,7 +210,7 @@ def ip_address_validators(protocol, unpack_ipv4):
         raise ValueError("The protocol '%s' is unknown. Supported: %s"
                          % (protocol, ip_address_validator_map.keys()))
 
-comma_separated_int_list_re = re.compile('^[\d,]+$')
+comma_separated_int_list_re = re.compile('^[\d,]+\Z')
 validate_comma_separated_integer_list = RegexValidator(comma_separated_int_list_re, _(u'Enter only digits separated by commas.'), 'invalid')
 
 
@@ -249,4 +254,3 @@ class MaxLengthValidator(BaseValidator):
     clean   = lambda self, x: len(x)
     message = _(u'Ensure this value has at most %(limit_value)d characters (it has %(show_value)d).')
     code = 'max_length'
-

docs/releases/1.4.21.txt

@@ -26,3 +26,29 @@ As each built-in session backend was fixed separately (rather than a fix in the
 core sessions framework), maintainers of third-party session backends should
 check whether the same vulnerability is present in their backend and correct
 it if so.
+
+Header injection possibility since validators accept newlines in input
+======================================================================
+
+Some of Django's built-in validators
+(``django.core.validators.EmailValidator``, most seriously) didn't
+prohibit newline characters (due to the usage of ``$`` instead of ``\Z`` in the
+regular expressions). If you use values with newlines in HTTP response or email
+headers, you can suffer from header injection attacks. Django itself isn't
+vulnerable because :class:`~django.http.HttpResponse` and the mail sending
+utilities in :mod:`django.core.mail` prohibit newlines in HTTP and SMTP
+headers, respectively. While the validators have been fixed in Django, if
+you're creating HTTP responses or email messages in other ways, it's a good
+idea to ensure that those methods prohibit newlines as well. You might also
+want to validate that any existing data in your application doesn't contain
+unexpected newlines.
+
+:func:`~django.core.validators.validate_ipv4_address`,
+:func:`~django.core.validators.validate_slug`, and
+:class:`~django.core.validators.URLValidator` and their usage in the
+corresponding form fields ``GenericIPAddresseField``, ``IPAddressField``,
+``SlugField``, and ``URLField`` are also affected.
+
+The undocumented, internally unused ``validate_integer()`` function is now
+stricter as it validates using a regular expression instead of simply casting
+the value using ``int()`` and checking if an exception was raised.

tests/modeltests/validators/tests.py

@@ -11,14 +11,17 @@ from django.utils.unittest import TestCase
 NOW = datetime.now()
 
 TEST_DATA = (
+    # (validator, value, expected),
     # (validator, value, expected),
     (validate_integer, '42', None),
     (validate_integer, '-42', None),
     (validate_integer, -42, None),
-    (validate_integer, -42.5, None),
 
+    (validate_integer, -42.5, ValidationError),
     (validate_integer, None, ValidationError),
     (validate_integer, 'a', ValidationError),
+    (validate_integer, '\n42', ValidationError),
+    (validate_integer, '42\n', ValidationError),
 
     (validate_email, 'email@here.com', None),
     (validate_email, 'weirder-email@here.and.there.com', None),
@@ -33,6 +36,11 @@ TEST_DATA = (
     # Quoted-string format (CR not allowed)
     (validate_email, '"\\\011"@here.com', None),
     (validate_email, '"\\\012"@here.com', ValidationError),
+    # Trailing newlines in username or domain not allowed
+    (validate_email, 'a@b.com\n', ValidationError),
+    (validate_email, 'a\n@b.com', ValidationError),
+    (validate_email, '"test@test"\n@example.com', ValidationError),
+    (validate_email, 'a@[127.0.0.1]\n', ValidationError),
 
     (validate_slug, 'slug-ok', None),
     (validate_slug, 'longer-slug-still-ok', None),
@@ -45,6 +53,7 @@ TEST_DATA = (
     (validate_slug, 'some@mail.com', ValidationError),
     (validate_slug, '你好', ValidationError),
     (validate_slug, '\n', ValidationError),
+    (validate_slug, 'trailing-newline\n', ValidationError),
 
     (validate_ipv4_address, '1.1.1.1', None),
     (validate_ipv4_address, '255.0.0.0', None),
@@ -54,6 +63,7 @@ TEST_DATA = (
     (validate_ipv4_address, '25.1.1.', ValidationError),
     (validate_ipv4_address, '25,1,1,1', ValidationError),
     (validate_ipv4_address, '25.1 .1.1', ValidationError),
+    (validate_ipv4_address, '1.1.1.1\n', ValidationError),
 
     # validate_ipv6_address uses django.utils.ipv6, which
     # is tested in much greater detail in it's own testcase
@@ -87,6 +97,7 @@ TEST_DATA = (
     (validate_comma_separated_integer_list, '', ValidationError),
     (validate_comma_separated_integer_list, 'a,b,c', ValidationError),
     (validate_comma_separated_integer_list, '1, 2, 3', ValidationError),
+    (validate_comma_separated_integer_list, '1,2,3\n', ValidationError),
 
     (MaxValueValidator(10), 10, None),
     (MaxValueValidator(10), -10, None),
@@ -138,6 +149,9 @@ TEST_DATA = (
     (URLValidator(), 'http://-invalid.com', ValidationError),
     (URLValidator(), 'http://inv-.alid-.com', ValidationError),
     (URLValidator(), 'http://inv-.-alid.com', ValidationError),
+    # Trailing newlines not accepted
+    (URLValidator(), 'http://www.djangoproject.com/\n', ValidationError),
+    (URLValidator(), 'http://[::ffff:192.9.5.5]\n', ValidationError),
 
     (BaseValidator(True), True, None),
     (BaseValidator(True), False, ValidationError),