diff --git a/django/http/request.py b/django/http/request.py
index b50392abd2..15f1c4614e 100644
--- a/django/http/request.py
+++ b/django/http/request.py
@@ -68,8 +68,11 @@ class HttpRequest(object):
             '<%s: %s %r>' % (self.__class__.__name__, self.method, force_str(self.get_full_path()))
         )
 
-    def get_host(self):
-        """Returns the HTTP host using the environment or request headers."""
+    def _get_raw_host(self):
+        """
+        Return the HTTP host using the environment or request headers. Skip
+        allowed hosts protection, so may return an insecure host.
+        """
         # We try three options, in order of decreasing preference.
         if settings.USE_X_FORWARDED_HOST and (
                 'HTTP_X_FORWARDED_HOST' in self.META):
@@ -82,6 +85,11 @@ class HttpRequest(object):
             server_port = self.get_port()
             if server_port != ('443' if self.is_secure() else '80'):
                 host = '%s:%s' % (host, server_port)
+        return host
+
+    def get_host(self):
+        """Return the HTTP host using the environment or request headers."""
+        host = self._get_raw_host()
 
         # There is no hostname validation when DEBUG=True
         if settings.DEBUG:
@@ -138,6 +146,17 @@ class HttpRequest(object):
                 raise
         return value
 
+    def get_raw_uri(self):
+        """
+        Return an absolute URI from variables available in this request. Skip
+        allowed hosts protection, so may return insecure URI.
+        """
+        return '{scheme}://{host}{path}'.format(
+            scheme=self.scheme,
+            host=self._get_raw_host(),
+            path=self.get_full_path(),
+        )
+
     def build_absolute_uri(self, location=None):
         """
         Builds an absolute URI from the location and the variables available in
diff --git a/django/views/debug.py b/django/views/debug.py
index 4f96ac320c..55357b3344 100644
--- a/django/views/debug.py
+++ b/django/views/debug.py
@@ -669,7 +669,7 @@ TECHNICAL_500_TEMPLATE = ("""
     </tr>
     <tr>
       <th>Request URL:</th>
-      <td>{{ request.build_absolute_uri|escape }}</td>
+      <td>{{ request.get_raw_uri|escape }}</td>
     </tr>
 {% endif %}
     <tr>
@@ -849,7 +849,7 @@ Environment:
 
 {% if request %}
 Request Method: {{ request.META.REQUEST_METHOD }}
-Request URL: {{ request.build_absolute_uri|escape }}
+Request URL: {{ request.get_raw_uri|escape }}
 {% endif %}
 Django Version: {{ django_version_info }}
 Python Version: {{ sys_version_info }}
@@ -1048,7 +1048,7 @@ TECHNICAL_500_TEXT_TEMPLATE = ("""{% firstof exception_type 'Report' %}{% if req
 {% firstof exception_value 'No exception message supplied' %}
 {% if request %}
 Request Method: {{ request.META.REQUEST_METHOD }}
-Request URL: {{ request.build_absolute_uri }}{% endif %}
+Request URL: {{ request.get_raw_uri }}{% endif %}
 Django Version: {{ django_version_info }}
 Python Executable: {{ sys_executable }}
 Python Version: {{ sys_version_info }}
diff --git a/tests/logging_tests/tests.py b/tests/logging_tests/tests.py
index 0b4abbfef6..9c39bb2d59 100644
--- a/tests/logging_tests/tests.py
+++ b/tests/logging_tests/tests.py
@@ -352,6 +352,25 @@ class AdminEmailHandlerTest(SimpleTestCase):
         self.assertEqual(len(mail.outbox), 1)
         self.assertEqual(mail.outbox[0].to, ['manager@example.com'])
 
+    @override_settings(ALLOWED_HOSTS='example.com')
+    def test_disallowed_host_doesnt_crash(self):
+        admin_email_handler = self.get_admin_email_handler(self.logger)
+        old_include_html = admin_email_handler.include_html
+
+        # Text email
+        admin_email_handler.include_html = False
+        try:
+            self.client.get('/', HTTP_HOST='evil.com')
+        finally:
+            admin_email_handler.include_html = old_include_html
+
+        # HTML email
+        admin_email_handler.include_html = True
+        try:
+            self.client.get('/', HTTP_HOST='evil.com')
+        finally:
+            admin_email_handler.include_html = old_include_html
+
 
 class SettingsConfigTest(AdminScriptTestCase):
     """
diff --git a/tests/requests/tests.py b/tests/requests/tests.py
index 8a0b32d1c0..3a3d7e7733 100644
--- a/tests/requests/tests.py
+++ b/tests/requests/tests.py
@@ -502,6 +502,18 @@ class RequestsTests(SimpleTestCase):
         with self.assertRaises(UnreadablePostError):
             request.FILES
 
+    @override_settings(ALLOWED_HOSTS=['example.com'])
+    def test_get_raw_uri(self):
+        factory = RequestFactory(HTTP_HOST='evil.com')
+        request = factory.get('////absolute-uri')
+        self.assertEqual(request.get_raw_uri(), 'http://evil.com//absolute-uri')
+
+        request = factory.get('/?foo=bar')
+        self.assertEqual(request.get_raw_uri(), 'http://evil.com/?foo=bar')
+
+        request = factory.get('/path/with:colons')
+        self.assertEqual(request.get_raw_uri(), 'http://evil.com/path/with:colons')
+
 
 class HostValidationTests(SimpleTestCase):
     poisoned_hosts = [
diff --git a/tests/view_tests/tests/test_debug.py b/tests/view_tests/tests/test_debug.py
index 4f3a9d6161..b4e7f9c7fa 100644
--- a/tests/view_tests/tests/test_debug.py
+++ b/tests/view_tests/tests/test_debug.py
@@ -439,6 +439,14 @@ class ExceptionReporterTests(SimpleTestCase):
             "Evaluation exception reason not mentioned in traceback"
         )
 
+    @override_settings(ALLOWED_HOSTS='example.com')
+    def test_disallowed_host(self):
+        "An exception report can be generated even for a disallowed host."
+        request = self.rf.get('/', HTTP_HOST='evil.com')
+        reporter = ExceptionReporter(request, None, None, None)
+        html = reporter.get_traceback_html()
+        self.assertIn("http://evil.com/", html)
+
 
 class PlainTextReportTests(SimpleTestCase):
     rf = RequestFactory()
@@ -495,6 +503,14 @@ class PlainTextReportTests(SimpleTestCase):
         reporter = ExceptionReporter(None, None, "I'm a little teapot", None)
         reporter.get_traceback_text()
 
+    @override_settings(ALLOWED_HOSTS='example.com')
+    def test_disallowed_host(self):
+        "An exception report can be generated even for a disallowed host."
+        request = self.rf.get('/', HTTP_HOST='evil.com')
+        reporter = ExceptionReporter(request, None, None, None)
+        text = reporter.get_traceback_text()
+        self.assertIn("http://evil.com/", text)
+
 
 class ExceptionReportTestMixin(object):