taken from:
http://security.ubuntu.com/ubuntu/pool/main/m/mailman/mailman_2.1.5-9ubuntu4.4.diff.gz

--- Mailman/Cgi/confirm.py	2009-12-22 18:00:43.000000000 +0000
+++ Mailman/Cgi/confirm.py.oden	2011-02-23 09:52:44.000000000 +0000
@@ -469,7 +469,7 @@ def unsubscription_prompt(mlist, doc, co
     if fullname is None:
         fullname = _('<em>Not available</em>')
     else:
-        fullname = Utils.uncanonstr(fullname, lang)
+        fullname = Utils.websafe(Utils.uncanonstr(fullname, lang))
     table.AddRow([_("""Your confirmation is required in order to complete the
     unsubscription request from the mailing list <em>%(listname)s</em>.  You
     are currently subscribed with
@@ -571,7 +571,7 @@ def addrchange_prompt(mlist, doc, cookie
     if fullname is None:
         fullname = _('<em>Not available</em>')
     else:
-        fullname = Utils.uncanonstr(fullname, lang)
+        fullname = Utils.websafe(Utils.uncanonstr(fullname, lang))
     if globally:
         globallys = _('globally')
     else:
@@ -812,7 +812,7 @@ def reenable_prompt(mlist, doc, cookie,
     if username is None:
         username = _('<em>not available</em>')
     else:
-        username = Utils.uncanonstr(username, lang)
+        username = Utils.websafe(Utils.uncanonstr(username, lang))
 
     table.AddRow([_("""Your membership in the %(realname)s mailing list is
     currently disabled due to excessive bounces.  Your confirmation is