Millionaire Mode

Identify the weakness in the below JSP file:

1  ...   
2  <input type=button name="back" value="Back" onClick="javascript:doBack()">   
3    
4  <%   
5  if("Admin".equals(session.getAttribute("user-type")))   
6  {   
7  %>   
8  <input type=button name="Delete Users" value="View Stock"  onClick="javascript:doDelete()">   
9  <%  
10  }%>  
11  </form>  
12   
13  <script>  
14  function doBack()  
15  {  
16   history.go(-1);  
17  }  
18  function doDelete()  
19  {  
20   document.forms[0].action="/DeleteUsersAction";  
21   document.forms[0].submit();  
22  }  
23  </script>  
24  ...