# Unsanitized user input in raw HTML strings (XSS)

## Overview

* **Rule ID**: `javascript_lang_raw_html_using_user_input`
* **Applicable Languages**: Javascript
* **Weakness ID**: CWE-79

## Description

Embedding unsanitized user input in HTML makes your application vulnerable to cross-site scripting (XSS) attacks. This flaw permits attackers to insert harmful scripts into web pages accessed by other users.

## Remediation Guidelines

* **Avoid** embedding user input straight into HTML strings. Doing so can cause XSS vulnerabilities.

  ```javascript
  const html = <h1>${req.params.title}</h1> // insecure

  ```
* **Make sure to use** a framework or templating language that automatically processes the encoding and sanitizing of user input while forming HTML. This method reduces the likelihood of XSS attacks.
* **Sanitize user input** if directly using HTML strings is unavoidable. Use libraries intended for input sanitization to ensure user input is free of malicious content.

  ```javascript
  import sanitizeHtml from 'sanitize-html'

  const sanitizedTitle = sanitizeHtml(req.params.title)
  const html = `<h1>${sanitizedTitle}</h1>`
  ```

## References

* [**OWASP Cross-Site Scripting (XSS) Cheatsheet**](https://cheatsheetseries.owasp.org/cheatsheets/Cross_Site_Scripting_Prevention_Cheat_Sheet.html)
* [**CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')**](https://cwe.mitre.org/data/definitions/79.html)
* [**OWASP Top 10: A03:2021 - Injection**](https://owasp.org/Top10/A03_2021-Injection/)

## 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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