diff -r 1c9208fa9127 roundup/cgi/client.py
--- a/roundup/cgi/client.py	Sat Feb 16 16:12:37 2019 -0500
+++ b/roundup/cgi/client.py	Sun Feb 17 16:52:08 2019 +0100
@@ -1110,9 +1110,9 @@
                 header_pass += 1
                 
         enforce=config['WEB_CSRF_ENFORCE_HEADER_X-FORWARDED-HOST']
-        if 'HTTP_X-FORWARDED-HOST' in self.env:
+        if 'HTTP_X_FORWARDED_HOST' in self.env:
             if enforce != "no":
-                host = self.env['HTTP_X-FORWARDED-HOST']
+                host = self.env['HTTP_X_FORWARDED_HOST']
                 foundat = self.base.find('://' + host + '/')
                 # 4 means self.base has http:/ prefix, 5 means https:/ prefix
                 if foundat not in [4, 5]:
@@ -1159,7 +1159,7 @@
                 # Note we do not use CSRF nonces for xmlrpc requests.
                 #
                 # see: https://www.owasp.org/index.php/Cross-Site_Request_Forgery_(CSRF)_Prevention_Cheat_Sheet#Protecting_REST_Services:_Use_of_Custom_Request_Headers
-                if 'HTTP_X-REQUESTED-WITH' not in self.env:
+                if 'HTTP_X_REQUESTED_WITH' not in self.env:
                     logger.error(self._("csrf X-REQUESTED-WITH xmlrpc required header check failed for user%s."), current_user)
                     raise UsageError(self._("Required Header Missing"))
 
diff -r 1c9208fa9127 roundup/scripts/roundup_server.py
--- a/roundup/scripts/roundup_server.py	Sat Feb 16 16:12:37 2019 -0500
+++ b/roundup/scripts/roundup_server.py	Sun Feb 17 16:52:08 2019 +0100
@@ -411,7 +411,7 @@
             # If behind a proxy, this is the hostname supplied
             # via the Host header to the proxy. Used by core code.
             # Controlled by the CSRF settings.
-            env['HTTP_X-FORWARDED-HOST'] = xfh
+            env['HTTP_X_FORWARDED_HOST'] = xfh
         xff = self.headers.get('X-Forwarded-For', None)
         if xff:
             # xff is a list of ip addresses for original client/proxies:
@@ -421,7 +421,7 @@
             # Made available for extensions if the user trusts it.
             # E.g. you may wish to disable recaptcha validation extension
             # if the ip of the client matches 172.16.0.0.
-            env['HTTP_X-FORWARDED-FOR'] = xff
+            env['HTTP_X_FORWARDED_FOR'] = xff
         xfp = self.headers.get('X-Forwarded-Proto', None)
         if xfp:
             # xfp is the protocol (http/https) seen by proxies in the
@@ -435,7 +435,7 @@
             # May not be trustworthy. Do not use in core without
             # config option to control its use.
             # Made available for extensions if the user trusts it.
-            env['HTTP_X-FORWARDED-PROTO'] = xfp
+            env['HTTP_X_FORWARDED_PROTO'] = xfp
         if 'CGI_SHOW_TIMING' in os.environ:
             env['CGI_SHOW_TIMING'] = os.environ['CGI_SHOW_TIMING']
         env['HTTP_ACCEPT_LANGUAGE'] = self.headers.get('accept-language')
@@ -447,7 +447,7 @@
             env['HTTP_ORIGIN'] = origin
         xrw = self.headers.get('x-requested-with')
         if xrw:
-            env['HTTP_X-REQUESTED-WITH'] = xrw
+            env['HTTP_X_REQUESTED_WITH'] = xrw
         range = self.headers.get('range')
         if range:
             env['HTTP_RANGE'] = range
diff -r 1c9208fa9127 test/test_cgi.py
--- a/test/test_cgi.py	Sat Feb 16 16:12:37 2019 -0500
+++ b/test/test_cgi.py	Sun Feb 17 16:52:08 2019 +0100
@@ -904,7 +904,7 @@
         del(cl.env['HTTP_ORIGIN'])
         del(out[0])
 
-        cl.env['HTTP_X-FORWARDED-HOST'] = 'whoami.com'
+        cl.env['HTTP_X_FORWARDED_HOST'] = 'whoami.com'
         # if there is an X-FORWARDED-HOST header it is used and
         # HOST header is ignored. X-FORWARDED-HOST should only be
         # passed/set by a proxy. In this case the HOST header is
@@ -915,7 +915,7 @@
         match_at=out[0].find('Redirecting to <a href="http://whoami.com/path/issue1?@ok_message')
         print("result of subtest 4:", out[0])
         self.assertNotEqual(match_at, -1)
-        del(cl.env['HTTP_X-FORWARDED-HOST'])
+        del(cl.env['HTTP_X_FORWARDED_HOST'])
         del(cl.env['HTTP_HOST'])
         del(out[0])
 
@@ -928,14 +928,14 @@
         del(out[0])
 
         # try failing headers
-        cl.env['HTTP_X-FORWARDED-HOST'] = 'whoami.net'
+        cl.env['HTTP_X_FORWARDED_HOST'] = 'whoami.net'
         # this raises an error as the header check passes and 
         # it did the edit and tries to send mail.
         cl.inner_main()
         match_at=out[0].find('Invalid X-FORWARDED-HOST whoami.net')
         print("result of subtest 6:", out[0])
         self.assertNotEqual(match_at, -1)
-        del(cl.env['HTTP_X-FORWARDED-HOST'])
+        del(cl.env['HTTP_X_FORWARDED_HOST'])
         del(out[0])
 
         # header checks succeed
@@ -1047,7 +1047,7 @@
                             'CONTENT_TYPE': 'text/plain',
                             'HTTP_AUTHORIZATION': 'Basic YWRtaW46YWRtaW4=',
                             'HTTP_REFERER': 'http://whoami.com/path/',
-                            'HTTP_X-REQUESTED-WITH': "XMLHttpRequest"
+                            'HTTP_X_REQUESTED_WITH': "XMLHttpRequest"
                         }, form)
         cl.db = self.db
         cl.base = 'http://whoami.com/path/'
@@ -1075,7 +1075,7 @@
         del(out[0])
 
         # remove the X-REQUESTED-WITH header and get an xmlrpc fault returned
-        del(cl.env['HTTP_X-REQUESTED-WITH'])
+        del(cl.env['HTTP_X_REQUESTED_WITH'])
         cl.handle_xmlrpc()
         frag_faultCode = "<member>\n<name>faultCode</name>\n<value><int>1</int></value>\n</member>\n"
         frag_faultString = "<member>\n<name>faultString</name>\n<value><string>&lt;class 'roundup.exceptions.UsageError'&gt;:Required Header Missing</string></value>\n</member>\n"