> For the complete documentation index, see [llms.txt](https://docs.sec1.io/user-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.sec1.io/user-docs/4-sast/3-javascript/permissive-origin-in-postmessage.md).

# Permissive origin in postMessage

## Overview

* **Rule ID**: `java_lang_information_leakage`
* **Applicable Languages**: Javascript
* **Weakness ID**: CWE-346

## Description

Using a permissive origin in `postMessage` calls presents a security risk. Setting the target origin to `"*"` in a `postMessage` call means that any website can receive the message, potentially exposing sensitive information to unauthorized parties.

## Remediation Guidelines

* **Do not** use `"*"` as the target origin in `postMessage` calls. This practice is insecure because it permits any website to receive the messages.

  ```javascript
  window.postMessage(message, '*'); // unsafe
  ```
* **Do** specify the precise origin of the target application when using `postMessage`. This ensures that only the intended recipient can access the message.

  ```javascript
  window.postMessage(message, 'https://myapp.example.com');
  ```

## References

* [**CWE-346: Origin Validation Error**](https://cwe.mitre.org/data/definitions/346.html)
* [**OWASP Top 10: A07:2021 - Identification and Authentication Failures**](https://owasp.org/Top10/A07_2021-Identification_and_Authentication_Failures/)

## Configuration

To omit this rule during a scan, and to provide you with continuous 24/7 code-level scanning, you can employ our [**SAST TOOL**](https://scopy.sec1.io/login)