CWE-488: Exposure of Data Element to Wrong Session
Description
The product does not sufficiently enforce boundaries between the states of different sessions, causing data to be provided to, or used by, the wrong session.
Submission Date :
July 19, 2006, midnight
Modification Date :
2023-06-29 00:00:00+00:00
Organization :
MITRE
Extended Description
Data can "bleed" from one session to another through member variables of singleton objects, such as Servlets, and objects from a shared pool.
In the case of Servlets, developers sometimes do not understand that, unless a Servlet implements the SingleThreadModel interface, the Servlet is a singleton; there is only one instance of the Servlet, and that single instance is used and re-used to handle multiple requests that are processed simultaneously by different threads. A common result is that developers use Servlet member fields in such a way that one user may inadvertently see another user's data. In other words, storing user data in Servlet member fields introduces a data access race condition.
Example - 1
The following Servlet stores the value of a request parameter in a member field and then later echoes the parameter value to the response output stream.
name = req.getParameter("name");...out.println(name + ", thanks for visiting!");String name;protected void doPost (HttpServletRequest req, HttpServletResponse res) {}public class GuestBook extends HttpServlet {}While this code will work perfectly in a single-user environment, if two users access the Servlet at approximately the same time, it is possible for the two request handler threads to interleave in the following way: Thread 1: assign "Dick" to name Thread 2: assign "Jane" to name Thread 1: print "Jane, thanks for visiting!" Thread 2: print "Jane, thanks for visiting!" Thereby showing the first user the second user's name.
Related Weaknesses
This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined to give an overview of the different insight to similar items that may exist at higher and lower levels of abstraction.
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