CWE-488 Base Draft

Exposure of Data Element to Wrong Session

This vulnerability occurs when an application fails to properly isolate data between different user sessions, allowing information from one user's session to leak into another's.

Definition

What is CWE-488?

This vulnerability occurs when an application fails to properly isolate data between different user sessions, allowing information from one user's session to leak into another's.
This flaw typically happens when application components, like singleton objects or pooled resources, are incorrectly used to store user-specific data. For instance, in Java Servlets, a single instance often handles requests for all users simultaneously. If a developer stores user data in the Servlet's member fields instead of the proper request or session scope, one user's data can become visible to another user, creating a race condition. To prevent this, always store user state in the appropriate session context (like `HttpSession`) or within local method variables, never in shared object fields. Ensure your design clearly separates per-request data from shared application data, and understand the threading model of your framework's components.
Real-world impact

Real-world CVEs caused by CWE-488

No public CVE references are linked to this CWE in MITRE's catalog yet.

How attackers exploit it

Step-by-step attacker path

  1. 1

    Identify a code path that handles untrusted input without validation.

  2. 2

    Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.

  3. 3

    Deliver the payload through a normal request and observe the application's reaction.

  4. 4

    Iterate until the response leaks data, executes attacker code, or escalates privileges.

Vulnerable code example

Vulnerable Java

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.

Vulnerable Java 
public class GuestBook extends HttpServlet {
  		String name;
  		protected void doPost (HttpServletRequest req, HttpServletResponse res) {
  			name = req.getParameter("name");
  			...
  			out.println(name + ", thanks for visiting!");
  		}
  }
Secure code example

Secure pseudo

Secure pseudo 
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
  const safe = validateAndEscape(input);
  return executeWithGuards(safe);
}
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist

How to prevent CWE-488

  • Architecture and Design Protect the application's sessions from information leakage. Make sure that a session's data is not used or visible by other sessions.
  • Testing Use a static analysis tool to scan the code for information leakage vulnerabilities (e.g. Singleton Member Field).
  • Architecture and Design In a multithreading environment, storing user data in Servlet member fields introduces a data access race condition. Do not use member fields to store information in the Servlet.
Detection signals

How to detect CWE-488

Automated Static Analysis High

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Plexicus auto-fix

Plexicus auto-detects CWE-488 and opens a fix PR in under 60 seconds.

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Frequently asked questions

Frequently asked questions

What is CWE-488?

This vulnerability occurs when an application fails to properly isolate data between different user sessions, allowing information from one user's session to leak into another's.

How serious is CWE-488?

MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.

What languages or platforms are affected by CWE-488?

MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.

How can I prevent CWE-488?

Protect the application's sessions from information leakage. Make sure that a session's data is not used or visible by other sessions. Use a static analysis tool to scan the code for information leakage vulnerabilities (e.g. Singleton Member Field).

How does Plexicus detect and fix CWE-488?

Plexicus's SAST engine matches the data-flow signature for CWE-488 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.

Where can I learn more about CWE-488?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/488.html. You can also reference OWASP and NIST documentation for adjacent guidance.

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