diff -r 2a38df26e009 Lib/httplib.py
--- a/Lib/httplib.py	Tue Sep 03 11:39:06 2013 -0500
+++ b/Lib/httplib.py	Wed Sep 04 12:08:42 2013 +0200
@@ -214,6 +214,8 @@
 
 # maximal line length when calling readline().
 _MAXLINE = 65536
+_MAXHEADERS = 100
+
 
 class HTTPMessage(mimetools.Message):
 
@@ -271,6 +273,8 @@
         elif self.seekable:
             tell = self.fp.tell
         while True:
+            if len(hlist) > _MAXHEADERS:
+                raise TooManyHeaders()
             if tell:
                 try:
                     startofline = tell()
@@ -1270,6 +1274,11 @@
         HTTPException.__init__(self, "got more than %d bytes when reading %s"
                                      % (_MAXLINE, line_type))
 
+
+class TooManyHeaders(HTTPException):
+    def __init__(self):
+        HTTPException.__init__(self, "got more than %d headers" % _MAXHEADERS)
+
 # for backwards compatibility
 error = HTTPException
 
diff -r 2a38df26e009 Lib/test/test_httplib.py
--- a/Lib/test/test_httplib.py	Tue Sep 03 11:39:06 2013 -0500
+++ b/Lib/test/test_httplib.py	Wed Sep 04 12:08:42 2013 +0200
@@ -255,6 +255,13 @@
         if resp.read() != "":
             self.fail("Did not expect response from HEAD request")
 
+    def test_too_many_headers(self):
+        headers = '\r\n'.join('Header%d: foo' % i for i in xrange(200)) + '\r\n'
+        text = ('HTTP/1.1 200 OK\r\n' + headers)
+        s = FakeSocket(text)
+        r = httplib.HTTPResponse(s)
+        self.assertRaises(httplib.TooManyHeaders, r.begin)
+
     def test_send_file(self):
         expected = 'GET /foo HTTP/1.1\r\nHost: example.com\r\n' \
                    'Accept-Encoding: identity\r\nContent-Length:'