=== 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('<hr>')
         return
     code = cgi_info['html_code'].value
-    code = re.sub(r'<([/]?script.*?)>', r'&lt;\1&gt;', 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('<hr>')
+        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 <b>info</b> 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 <script> and </script> tags but nothing else.  Not the best
-        # solution, but expedient.
-        return re.sub(r'(?i)<([/]?script.*?)>', r'&lt;\1&gt;', 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('<', '&lt;')
-        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 = [
+    '<i?frame',
+    '<link',
+    '<meta',
+    '<script',
+    r'(?:^|\W)j(?:ava)?script(?:\W|$)',
+    r'(?:^|\W)vbs(?:cript)?(?:\W|$)',
+    r'(?:^|\W)domactivate(?:\W|$)',
+    r'(?:^|\W)domattrmodified(?:\W|$)',
+    r'(?:^|\W)domcharacterdatamodified(?:\W|$)',
+    r'(?:^|\W)domfocus(?:in|out)(?:\W|$)',
+    r'(?:^|\W)dommenuitem(?:in)?active(?:\W|$)',
+    r'(?:^|\W)dommousescroll(?:\W|$)',
+    r'(?:^|\W)domnodeinserted(?:intodocument)?(?:\W|$)',
+    r'(?:^|\W)domnoderemoved(?:fromdocument)?(?:\W|$)',
+    r'(?:^|\W)domsubtreemodified(?:\W|$)',
+    r'(?:^|\W)fscommand(?:\W|$)',
+    r'(?:^|\W)onabort(?:\W|$)',
+    r'(?:^|\W)on(?:de)?activate(?:\W|$)',
+    r'(?:^|\W)on(?:after|before)print(?:\W|$)',
+    r'(?:^|\W)on(?:after|before)update(?:\W|$)',
+    r'(?:^|\W)onbefore(?:(?:de)?activate|copy|cut|editfocus|paste)(?:\W|$)',
+    r'(?:^|\W)onbeforeunload(?:\W|$)',
+    r'(?:^|\W)onbegin(?:\W|$)',
+    r'(?:^|\W)onblur(?:\W|$)',
+    r'(?:^|\W)onbounce(?:\W|$)',
+    r'(?:^|\W)onbroadcast(?:\W|$)',
+    r'(?:^|\W)on(?:cell)?change(?:\W|$)',
+    r'(?:^|\W)oncheckboxstatechange(?:\W|$)',
+    r'(?:^|\W)on(?:dbl)?click(?:\W|$)',
+    r'(?:^|\W)onclose(?:\W|$)',
+    r'(?:^|\W)oncommand(?:update)?(?:\W|$)',
+    r'(?:^|\W)oncomposition(?:end|start)(?:\W|$)',
+    r'(?:^|\W)oncontextmenu(?:\W|$)',
+    r'(?:^|\W)oncontrolselect(?:\W|$)',
+    r'(?:^|\W)oncopy(?:\W|$)',
+    r'(?:^|\W)oncut(?:\W|$)',
+    r'(?:^|\W)ondataavailable(?:\W|$)',
+    r'(?:^|\W)ondataset(?:changed|complete)(?:\W|$)',
+    r'(?:^|\W)ondrag(?:drop|end|enter|exit|gesture|leave|over)?(?:\W|$)',
+    r'(?:^|\W)ondragstart(?:\W|$)',
+    r'(?:^|\W)ondrop(?:\W|$)',
+    r'(?:^|\W)onend(?:\W|$)',
+    r'(?:^|\W)onerror(?:update)?(?:\W|$)',
+    r'(?:^|\W)onfilterchange(?:\W|$)',
+    r'(?:^|\W)onfinish(?:\W|$)',
+    r'(?:^|\W)onfocus(?:in|out)?(?:\W|$)',
+    r'(?:^|\W)onhelp(?:\W|$)',
+    r'(?:^|\W)oninput(?:\W|$)',
+    r'(?:^|\W)onkey(?:up|down|press)(?:\W|$)',
+    r'(?:^|\W)onlayoutcomplete(?:\W|$)',
+    r'(?:^|\W)on(?:un)?load(?:\W|$)',
+    r'(?:^|\W)onlosecapture(?:\W|$)',
+    r'(?:^|\W)onmedia(?:complete|error)(?:\W|$)',
+    r'(?:^|\W)onmouse(?:down|enter|leave|move|out|over|up|wheel)(?:\W|$)',
+    r'(?:^|\W)onmove(?:end|start)?(?:\W|$)',
+    r'(?:^|\W)on(?:off|on)line(?:\W|$)',
+    r'(?:^|\W)onoutofsync(?:\W|$)',
+    r'(?:^|\W)onoverflow(?:changed)?(?:\W|$)',
+    r'(?:^|\W)onpage(?:hide|show)(?:\W|$)',
+    r'(?:^|\W)onpaint(?:\W|$)',
+    r'(?:^|\W)onpaste(?:\W|$)',
+    r'(?:^|\W)onpause(?:\W|$)',
+    r'(?:^|\W)onpopup(?:hidden|hiding|showing|shown)(?:\W|$)',
+    r'(?:^|\W)onprogress(?:\W|$)',
+    r'(?:^|\W)onpropertychange(?:\W|$)',
+    r'(?:^|\W)onradiostatechange(?:\W|$)',
+    r'(?:^|\W)onreadystatechange(?:\W|$)',
+    r'(?:^|\W)onrepeat(?:\W|$)',
+    r'(?:^|\W)onreset(?:\W|$)',
+    r'(?:^|\W)onresize(?:end|start)?(?:\W|$)',
+    r'(?:^|\W)onresume(?:\W|$)',
+    r'(?:^|\W)onreverse(?:\W|$)',
+    r'(?:^|\W)onrow(?:delete|enter|exit|inserted)(?:\W|$)',
+    r'(?:^|\W)onrows(?:delete|enter|inserted)(?:\W|$)',
+    r'(?:^|\W)onscroll(?:\W|$)',
+    r'(?:^|\W)onseek(?:\W|$)',
+    r'(?:^|\W)onselect(?:start)?(?:\W|$)',
+    r'(?:^|\W)onselectionchange(?:\W|$)',
+    r'(?:^|\W)onstart(?:\W|$)',
+    r'(?:^|\W)onstop(?:\W|$)',
+    r'(?:^|\W)onsubmit(?:\W|$)',
+    r'(?:^|\W)onsync(?:from|to)preference(?:\W|$)',
+    r'(?:^|\W)onsyncrestored(?:\W|$)',
+    r'(?:^|\W)ontext(?:\W|$)',
+    r'(?:^|\W)ontimeerror(?:\W|$)',
+    r'(?:^|\W)ontrackchange(?:\W|$)',
+    r'(?:^|\W)onunderflow(?:\W|$)',
+    r'(?:^|\W)onurlflip(?:\W|$)',
+    r'(?:^|\W)seeksegmenttime(?:\W|$)',
+    r'(?:^|\W)svgabort(?:\W|$)',
+    r'(?:^|\W)svgerror(?:\W|$)',
+    r'(?:^|\W)svgload(?:\W|$)',
+    r'(?:^|\W)svgresize(?:\W|$)',
+    r'(?:^|\W)svgscroll(?:\W|$)',
+    r'(?:^|\W)svgunload(?:\W|$)',
+    r'(?:^|\W)svgzoom(?:\W|$)',
+    ]
+
+
+# This is the actual re to look for the above patterns
+_badhtml = re.compile('|'.join(_badwords), re.IGNORECASE)
+# This is used to filter non-printable us-ascii characters, some of which
+# can be used to break words to avoid recognition.
+_filterchars = re.compile('[\000-\011\013\014\016-\037\177-\237]')
+# This is used to recognize '&#' and '%xx' strings for _translate which
+# translates them to characters
+_encodedchars = re.compile('(&#[0-9]+;?)|(&#x[0-9a-f]+;?)|(%[0-9a-f]{2})',
+                           re.IGNORECASE)
+
+
+def _translate(mo):
+    """Translate &#... and %xx encodings into the encoded character."""
+    match = mo.group().lower().strip('&#;')
+    try:
+        if match.startswith('x') or match.startswith('%'):
+            val = int(match[1:], 16)
+        else:
+            val = int(match, 10)
+    except ValueError:
+        return ''
+    if val < 256:
+        return chr(val)
+    else:
+        return ''
+
+
+def suspiciousHTML(html):
+    """Check HTML string for various tags, script language names and
+    'onxxx' actions that can be used in XSS attacks.
+    Currently, this a very simple minded test.  It just looks for
+    patterns without analyzing context.  Thus, it potentially flags lots
+    of benign stuff.
+    Returns True if anything suspicious found, False otherwise.
+    """
+
+    if _badhtml.search(_filterchars.sub(
+                       '', _encodedchars.sub(_translate, html))):
+        return True
+    else:
+        return False