# Unsanitized user input in HTTP request (SSRF)

## Overview

* **Rule ID**: `javascript_express_server_side_request_forgery`
* **Applicable Languages**: Javascript
* **Weakness ID**: CWE-918

## Description

Incorporating unsanitized user input directly into URLs for data retrieval exposes your application to server-side request forgery (SSRF) attacks. This vulnerability occurs when URLs include user-provided data without proper validation or sanitization.

## Remediation Guidelines

* **Do not** directly use user input to construct URLs for backend requests, as this can lead to SSRF vulnerabilities.

  ```javascript
  axios.get(`https://${req.params.host}`); // unsafe

  ```
* **Do validate** or sanitize user input before using it in URLs. Prefer using a predefined list of allowed hosts and map user input to this list to ensure only safe and expected URLs are constructed.

  ```javascript
  var host = "default-api.com";
  if (req.params.host === "something-else") {
  host = "other-api.com";
  }

  axios.get(`https://${host}`);
  ```

## References

* [**OWASP - Server-Side Request Forgery (SSRF) prevention cheat sheet**](https://cheatsheetseries.owasp.org/cheatsheets/Server_Side_Request_Forgery_Prevention_Cheat_Sheet.html)
* [**CWE-918: Server-Side Request Forgery (SSRF)**](https://cwe.mitre.org/data/definitions/918.html)
* [**OWASP Top 10: A10:2021 - Server-side Request Forgery (SSRF)**](https://owasp.org/Top10/A10_2021-Server-Side_Request_Forgery_%28SSRF%29/)

## 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)


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