What is Return of Wrong Status Code (CWE-393)?

TL;DR: Return of Wrong Status Code (CWE-393) is a vulnerability where incorrect status codes cause unexpected application behavior, leading to integrity issues and security misconfigurations.

What is Return of Wrong Status Code?

Return of Wrong Status Code (CWE-393) is a type of vulnerability where a function or operation returns an incorrect status code that does not accurately reflect the result of its execution. This can cause unexpected behavior in applications and lead to security misconfigurations.

As defined by the MITRE Corporation under CWE-393, and classified by the OWASP Foundation as Not directly mapped…

Quick Summary

Return of Wrong Status Code is a critical issue where incorrect status codes are returned, leading to unexpected application behavior. This can result in integrity issues, altered execution logic, and other unintended consequences. Jump to: Overview · How It Works · Business Impact · Attack Scenario · Detection · Fixes

Jump to: Quick Summary · Return of Wrong Status Code Overview · How Return of Wrong Status Code Works · Business Impact of Return of Wrong Status Code · Return of Wrong Status Code Attack Scenario · How to Detect Return of Wrong Status Code · How to Fix Return of Wrong Status Code · Framework-Specific Fixes for Return of Wrong Status Code · How to Ask AI to Check Your Code for Return of Wrong Status Code · Return of Wrong Status Code Best Practices Checklist · Return of Wrong Status Code FAQ · Vulnerabilities Related to Return of Wrong Status Code · References · Scan Your Own Site

Return of Wrong Status Code Overview

What

Return of Wrong Status Code (CWE-393) is a vulnerability where functions or operations return incorrect status codes.

Why it matters

Incorrect status codes can lead to unexpected application behavior, security misconfigurations, and integrity issues.

Where it occurs

This issue typically arises in backend applications that rely on accurate status code responses for proper operation.

Who is affected

Developers and organizations using any backend language are at risk if their functions return incorrect status codes.

Who is NOT affected

Applications that properly handle error conditions and ensure correct status code returns are not vulnerable to this weakness.

How Return of Wrong Status Code Works

Root Cause

The root cause lies in the improper handling or returning of status codes by a function, leading to unexpected application behavior.

Attack Flow

1. An attacker identifies a function that returns an incorrect status code.
2. The attacker exploits this condition to manipulate application logic or trigger security misconfigurations.
3. The application behaves unexpectedly due to the incorrect status code.

Prerequisites to Exploit

• A function must return an incorrect status code.
• The application must rely on accurate status codes for proper execution.

Vulnerable Code

def process_request(request):
    # Incorrect status code returned
    return 200, "Operation failed"

This code incorrectly returns a success status (200) when the operation has actually failed. This can mislead other parts of the application into assuming everything is fine.

Secure Code

def process_request(request):
    # Correct status code returned based on execution result
    if request.is_valid():
        return 200, "Operation successful"
    else:
        return 400, "Invalid request"

This secure version ensures that the correct status code is returned based on the actual outcome of the operation.

Business Impact of Return of Wrong Status Code

Integrity

Incorrect status codes can lead to unexpected application behavior and integrity issues by altering data or logic flow.

Other

Unexpected states caused by incorrect status codes can result in altered execution logic, leading to other unintended consequences.

• Financial loss due to operational disruptions.
• Compliance violations from security misconfigurations.
• Damage to reputation from system instability.

Return of Wrong Status Code Attack Scenario

1. An attacker identifies a function that returns an incorrect status code (e.g., 200 instead of 400).
2. The attacker exploits this condition by manipulating application logic or triggering security misconfigurations.
3. The application behaves unexpectedly, leading to potential data integrity issues and other unintended consequences.

How to Detect Return of Wrong Status Code

Manual Testing

• Review functions for proper status code handling.
• Ensure that error conditions return appropriate status codes.

Automated Scanners (SAST / DAST)

Static analysis can detect incorrect status code returns, while dynamic testing is needed to confirm actual behavior in runtime scenarios.

PenScan Detection

PenScan’s scanner engines such as ZAP and Wapiti can identify functions returning incorrect status codes.

False Positive Guidance

A real finding will show a function returning an incorrect status code that affects application logic. A false positive may occur if the pattern is present but does not actually impact behavior due to mitigating factors.

How to Fix Return of Wrong Status Code

• Ensure all functions return correct status codes based on their execution results.
• Implement proper error handling and validation for status codes.

Framework-Specific Fixes for Return of Wrong Status Code

Python/Django

def process_request(request):
    if request.is_valid():
        return JsonResponse({"status": "success"}, status=200)
    else:
        return JsonResponse({"status": "error", "message": "Invalid request"}, status=400)

How to Ask AI to Check Your Code for Return of Wrong Status Code

Return of Wrong Status Code Best Practices Checklist

✅ Ensure all functions return correct status codes based on their execution results. ✅ Implement proper error handling to validate status codes.

Return of Wrong Status Code FAQ

How does the Return of Wrong Status Code vulnerability work?

The function or operation returns an incorrect status code, leading to unexpected behavior in the application.

What are the real-world impacts of CWE-393?

It can lead to unexpected states and alter execution logic, potentially causing integrity issues and other unintended behaviors.

How do attackers exploit Return of Wrong Status Code?

Attackers take advantage of incorrect status codes to manipulate application behavior or trigger security misconfigurations.

What are the common detection methods for CWE-393?

Manual testing, automated scanners (SAST/DAST), and PenScan’s scanner engines can detect this vulnerability.

How do you fix Return of Wrong Status Code in Python applications?

Ensure that functions return correct status codes to prevent unexpected behavior and maintain application integrity.

What are the best practices for preventing CWE-393?

Implement proper error handling, validate status codes, and use secure coding practices to avoid incorrect status code returns.

How can I test my code for Return of Wrong Status Code vulnerabilities using an AI assistant?

Review your code with an AI assistant to identify potential CWE-393 issues and ensure correct status code handling.

Vulnerabilities Related to Return of Wrong Status Code

References

• MITRE - CWE-393
• NVD

Scan Your Own Site

Manual code review catches what you know to look for. An automated scan catches what you didn’t. Scan your own website using PenScan to find Return of Wrong Status Code and other risks before an attacker does.