=== modified file 'Mailman/Cgi/edithtml.py'
--- Mailman/Cgi/edithtml.py	2006-08-30 14:54:22 +0000
+++ Mailman/Cgi/edithtml.py	2007-12-04 19:52:18 +0000
@@ -1,4 +1,4 @@
-# Copyright (C) 1998-2006 by the Free Software Foundation, Inc.
+# Copyright (C) 1998-2007 by the Free Software Foundation, Inc.
 #
 # This program is free software; you can redistribute it and/or
 # modify it under the terms of the GNU General Public License
@@ -159,7 +159,20 @@
         doc.AddItem('
')
         return
     code = cgi_info['html_code'].value
-    code = re.sub(r'<([/]?script.*?)>', r'<\1>', code)
+    if Utils.suspiciousHTML(code):
+        doc.AddItem(Header(3,
+           _("""The page you saved contains suspicious HTML that could
+potentially expose your users to cross-site scripting attacks.  This change
+has therefore been rejected.  If you still want to make these changes, you
+must have shell access to your Mailman server.
+             """)))
+        doc.AddItem(_('See '))
+        doc.AddItem(Link(
+'http://www.python.org/cgi-bin/faqw-mm.py?req=show&file=faq04.048.htp',
+                _('FAQ 4.48.')))
+        doc.AddItem(Header(3,_("Page Unchanged.")))
+        doc.AddItem('
')
+        return
     langdir = os.path.join(mlist.fullpath(), mlist.preferred_language)
     # Make sure the directory exists
     omask = os.umask(0)
=== modified file 'Mailman/Gui/General.py'
--- Mailman/Gui/General.py	2006-08-30 14:54:22 +0000
+++ Mailman/Gui/General.py	2007-12-04 19:52:18 +0000
@@ -1,4 +1,4 @@
-# Copyright (C) 2001-2006 by the Free Software Foundation, Inc.
+# Copyright (C) 2001-2007 by the Free Software Foundation, Inc.
 #
 # This program is free software; you can redistribute it and/or
 # modify it under the terms of the GNU General Public License
@@ -436,17 +442,21 @@
             # Convert any html entities to Unicode
             mlist.subject_prefix = Utils.canonstr(
                 val, mlist.preferred_language)
+        elif property == 'info':
+            if val <> mlist.info:
+                if Utils.suspiciousHTML(val):
+                    doc.addError(_("""The info attribute you saved
+contains suspicious HTML that could potentially expose your users to cross-site
+scripting attacks.  This change has therefore been rejected.  If you still want
+to make these changes, you must have shell access to your Mailman server.
+This change can be made with bin/withlist or with bin/config_list by setting
+mlist.info.
+                        """))
+                else:
+                    mlist.info = val
         else:
             GUIBase._setValue(self, mlist, property, val, doc)
 
-    def _escape(self, property, value):
-        # The 'info' property allows HTML, but let's sanitize it to avoid XSS
-        # exploits.  Everything else should be fully escaped.
-        if property <> 'info':
-            return GUIBase._escape(self, property, value)
-        # Sanitize  tags but nothing else.  Not the best
-        # solution, but expedient.
-        return re.sub(r'(?i)<([/]?script.*?)>', r'<\1>', value)
 
     def _postValidate(self, mlist, doc):
         if not mlist.reply_to_address.strip() and \
=== modified file 'Mailman/Gui/GUIBase.py'
--- Mailman/Gui/GUIBase.py	2005-08-27 01:40:17 +0000
+++ Mailman/Gui/GUIBase.py	2007-11-18 20:01:26 +0000
@@ -1,4 +1,4 @@
-# Copyright (C) 2002-2004 by the Free Software Foundation, Inc.
+# Copyright (C) 2002-2007 by the Free Software Foundation, Inc.
 #
 # This program is free software; you can redistribute it and/or
 # modify it under the terms of the GNU General Public License
@@ -12,7 +12,8 @@
 #
 # You should have received a copy of the GNU General Public License
 # along with this program; if not, write to the Free Software
-# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+# USA.
 
 """Base class for all web GUI components."""
 
@@ -122,10 +127,6 @@
         # Validate all the attributes for this category
         pass
 
-    def _escape(self, property, value):
-        value = value.replace('<', '<')
-        return value
-
     def handleForm(self, mlist, category, subcat, cgidata, doc):
         for item in self.GetConfigInfo(mlist, category, subcat):
             # Skip descriptions and legacy non-attributes
@@ -144,10 +145,9 @@
             elif not cgidata.has_key(property):
                 continue
             elif isinstance(cgidata[property], ListType):
-                val = [self._escape(property, x.value)
-                       for x in cgidata[property]]
+                val = [x.value for x in cgidata[property]]
             else:
-                val = self._escape(property, cgidata[property].value)
+                val = cgidata[property].value
             # Coerce the value to the expected type, raising exceptions if the
             # value is invalid.
             try:
=== modified file 'Mailman/Utils.py'
--- Mailman/Utils.py	2007-11-25 08:04:30 +0000
+++ Mailman/Utils.py	2007-12-04 19:52:18 +0000
@@ -876,3 +876,154 @@
     except (LookupError, UnicodeError, ValueError, HeaderParseError):
         # possibly charset problem. return with undecoded string in one line.
         return EMPTYSTRING.join(s.splitlines())
+
+
+# Patterns and functions to flag possible XSS attacks in HTML.
+# This list is compiled from information at http://ha.ckers.org/xss.html,
+# http://www.quirksmode.org/js/events_compinfo.html,
+# http://www.htmlref.com/reference/appa/events1.htm,
+# http://lxr.mozilla.org/mozilla/source/content/events/src/nsDOMEvent.cpp#59,
+# http://www.w3.org/TR/DOM-Level-2-Events/events.html and
+# http://www.xulplanet.com/references/elemref/ref_EventHandlers.html
+# Many thanks are due to Moritz Naumann for his assistance with this.
+_badwords = [
+    '