diff --git a/Lib/test/test_wsgiref.py b/Lib/test/test_wsgiref.py
index bce33291c566e1..2ea10889366519 100644
--- a/Lib/test/test_wsgiref.py
+++ b/Lib/test/test_wsgiref.py
@@ -525,6 +525,40 @@ def testExtras(self):
             '\r\n'
         )
 
+    validation_cases = (
+        ('Invalid\r\nName', 'ValidValue'),
+        ('Invalid\rName', 'ValidValue'),
+        ('Invalid\nName', 'ValidValue'),
+        ('\r\nInvalidName', 'ValidValue'),
+        ('\rInvalidName', 'ValidValue'),
+        ('\nInvalidName', 'ValidValue'),
+        (' InvalidName', 'ValidValue'),
+        ('\tInvalidName', 'ValidValue'),
+        ('Invalid:Name', 'ValidValue'),
+        (':InvalidName', 'ValidValue'),
+        ('ValidName', 'Invalid\r\nValue'),
+        ('ValidName', 'Invalid\rValue'),
+        ('ValidName', 'Invalid\nValue'),
+        ('ValidName', 'InvalidValue\r\n'),
+        ('ValidName', 'InvalidValue\r'),
+        ('ValidName', 'InvalidValue\n'),
+        (b'InvalidName', 'ValidValue', AssertionError),
+        ('ValidName', b'InvalidValue', AssertionError)
+    )
+
+    def test_add_header_validation(self):
+        h = Headers([])
+        for name, value, *exception in self.validation_cases:
+            with self.subTest((name, value, exception)):
+                with self.assertRaises(exception[0]) if len(exception) else self.assertRaisesRegex(ValueError, 'Invalid header'):
+                    h.add_header(name, value)
+
+    def test_initialize_validation(self):
+        for name, value, *exception in self.validation_cases:
+            with self.subTest((name, value, exception)):
+                with self.assertRaises(exception[0]) if len(exception) else self.assertRaisesRegex(ValueError, 'Invalid header'):
+                    Headers([(name, value)])
+
 class ErrorHandler(BaseCGIHandler):
     """Simple handler subclass for testing BaseHandler"""
 
diff --git a/Lib/wsgiref/headers.py b/Lib/wsgiref/headers.py
index fab851c5a44430..e53f47fdce47cf 100644
--- a/Lib/wsgiref/headers.py
+++ b/Lib/wsgiref/headers.py
@@ -10,6 +10,8 @@
 import re
 tspecials = re.compile(r'[ \(\)<>@,;:\\"/\[\]\?=]')
 
+from http.client import _is_legal_header_name, _is_illegal_header_value
+
 def _formatparam(param, value=None, quote=1):
     """Convenience function to format and return a key=value pair.
 
@@ -32,7 +34,9 @@ def __init__(self, headers=None):
         headers = headers if headers is not None else []
         if type(headers) is not list:
             raise TypeError("Headers must be a list of name/value tuples")
-        self._headers = headers
+        self._headers = []
+        for header, value in headers:
+            self.add_header(header, value)
         if __debug__:
             for k, v in headers:
                 self._convert_string_type(k)
@@ -52,8 +56,7 @@ def __len__(self):
     def __setitem__(self, name, val):
         """Set the value of a header."""
         del self[name]
-        self._headers.append(
-            (self._convert_string_type(name), self._convert_string_type(val)))
+        self.add_header(name, val)
 
     def __delitem__(self,name):
         """Delete all occurrences of a header, if present.
@@ -148,8 +151,7 @@ def setdefault(self,name,value):
         and value 'value'."""
         result = self.get(name)
         if result is None:
-            self._headers.append((self._convert_string_type(name),
-                self._convert_string_type(value)))
+            self.add_header(name, value)
             return value
         else:
             return result
@@ -181,4 +183,10 @@ def add_header(self, _name, _value, **_params):
             else:
                 v = self._convert_string_type(v)
                 parts.append(_formatparam(k.replace('_', '-'), v))
-        self._headers.append((self._convert_string_type(_name), "; ".join(parts)))
+        header = self._convert_string_type(_name)
+        value = "; ".join(parts)
+        if not _is_legal_header_name(header.encode('ascii')):
+            raise ValueError('Invalid header name %r' % (header,))
+        if _is_illegal_header_value(value.encode('ascii')):
+            raise ValueError('Invalid header value %r' % (value,))
+        self._headers.append((header, value))
diff --git a/Misc/NEWS.d/next/Security/2019-08-27-01-08-25.bpo-11671.wfJY-D.rst b/Misc/NEWS.d/next/Security/2019-08-27-01-08-25.bpo-11671.wfJY-D.rst
new file mode 100644
index 00000000000000..4d3334713610c5
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2019-08-27-01-08-25.bpo-11671.wfJY-D.rst
@@ -0,0 +1 @@
+Add validation in wsgiref.headers.Headers to disallow invalid characters in header names and values. Patch by Ashwin Ramaswami, initial patch by Devin Cook.