CWE-430 Base Incomplete

Deployment of Wrong Handler

This vulnerability occurs when a system incorrectly assigns or routes an object to the wrong processing component.

Definition

What is CWE-430?

This vulnerability occurs when a system incorrectly assigns or routes an object to the wrong processing component.
Deploying the wrong handler is a misconfiguration or logic flaw where an application sends data or a request to an unintended processing module. For instance, this could involve mistakenly routing a request for a JSP file's source code to a servlet designed to display it, rather than to the component that executes it. Such incorrect routing often bypasses the intended security controls and business logic, exposing the underlying system to unintended behavior. This issue frequently stems from flawed type-determination logic, where the system automatically infers how to handle an object, overriding an explicitly declared type. Developers encounter this when trust is placed in dynamic dispatch mechanisms, file upload handlers, or content-type resolvers that make incorrect assumptions. The core risk is that the wrong handler processes sensitive data or commands, potentially leading to information disclosure, code execution, or system manipulation.
Real-world impact

Real-world CVEs caused by CWE-430

  • Source code disclosure via manipulated file extension that causes parsing by wrong DLL.

  • Web browser does not properly handle the Content-Type header field, causing a different application to process the document.

  • Source code disclosure by directly invoking a servlet.

  • Arbitrary Perl functions can be loaded by calling a non-existent function that activates a handler.

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 pseudo

MITRE has not published a code example for this CWE. The pattern below is illustrative — see Resources for canonical references.

Vulnerable pseudo
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}
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-430

  • Architecture and Design Perform a type check before interpreting an object.
  • Architecture and Design Reject any inconsistent types, such as a file with a .GIF extension that appears to consist of PHP code.
Detection signals

How to detect CWE-430

SAST High

Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.

DAST Moderate

Run dynamic application security testing against the live endpoint.

Runtime Moderate

Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.

Code review Moderate

Code review: flag any new code that handles input from this surface without using the validated framework helpers.

Plexicus auto-fix

Plexicus auto-detects CWE-430 and opens a fix PR in under 60 seconds.

Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.

Frequently asked questions

Frequently asked questions

What is CWE-430?

This vulnerability occurs when a system incorrectly assigns or routes an object to the wrong processing component.

How serious is CWE-430?

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-430?

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

How can I prevent CWE-430?

Perform a type check before interpreting an object. Reject any inconsistent types, such as a file with a .GIF extension that appears to consist of PHP code.

How does Plexicus detect and fix CWE-430?

Plexicus's SAST engine matches the data-flow signature for CWE-430 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-430?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/430.html. You can also reference OWASP and NIST documentation for adjacent guidance.

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