HTML injection poses a serious threat to web applications, allowing attackers to manipulate websites and compromise user data. In this comprehensive guide, we’ll delve into both beginner-friendly and advanced aspects of HTML injection. its also OWASP Top10 vulnerability Whether you’re new to web security or an experienced professional, this article will equip you with the knowledge to understand, prevent, and exploit HTML injection vulnerabilities.


HTML Injection Basics (Beginner’s Section)


What is HTML Injection?

HTML injection involves injecting malicious HTML code into a website to alter its appearance or compromise user data. Attackers exploit vulnerabilities in input fields, manipulating the website’s design and potentially stealing sensitive information.


Types of HTML Injection

  1. Reflected HTML Injection:
    • The injected code is reflected back to users without permanent storage on the server.
    • Example payload:<html><script>alert('Vulnerable to HTML Injection!');</script></html>


      2. Stored HTML Injection:

    • Malicious code is permanently stored on the server and displayed to multiple users.
    • Example payload: <script> // Malicious code to steal user cookies...</script>


      3. DOM-based HTML Injection:

    • Injected code manipulates the Document Object Model (DOM) dynamically within the user’s browser.
    • Example payload: Dynamically updating the DOM with user input and injecting a payload.


      4. Blind HTML Injection:

    • The attacker doesn’t directly observe the results but expects actions affecting other users or the system.
    • Example payload: <img src="<script> // Malicious code...</script>">


Prevention Strategies (Beginner’s Tips)

  • Implement proper input validation and output encoding to sanitize user-generated content.
  • Validate user input against a whitelist of allowed characters and HTML tags.
  • Use output encoding when displaying user-generated content to prevent interpretation as HTML or JavaScript.
  • Regularly update web browsers and client-side libraries for the latest security patches.


Advanced HTML Injection Techniques

Obfuscated Payloads

Attackers may use techniques like character encoding and code obfuscation to evade detection. Example: var payload = "&#x3c;&#x73;&#x63;...";


Polyglot Payloads

Malicious code interpreted as multiple languages or file types.

Example: <script> var payload = '<img src="x" onerror="javascript:alert(\'XSS\')"></script>';


Framework-Specific Exploits

Leveraging vulnerabilities or weaknesses in web application frameworks. Requires in-depth knowledge of the targeted framework.



HTML Injection with XSS

Combining HTML injection with cross-site scripting (XSS) to execute arbitrary JavaScript code.

Example: <img src="x" onload="javascript:alert(document.cookie)">


HTML Injection with SQL Injection

Combining HTML injection with SQL injection for advanced attacks.

Example: SQL injection payload embedded in HTML injection code.


Exploiting HTML Injection (Tips for Assessing Severity)

  1. Examine all input fields for potential vulnerabilities.
  2. Test HTML Injection as an alternative to XSS attacks.
  3. Utilize meta tags for unexpected behaviors, such as redirection.



HTML injection is a multifaceted threat with both beginner-friendly and advanced exploitation techniques. Developers and security professionals must stay vigilant, employ secure coding practices, and regularly test web applications for vulnerabilities. Understanding the basics and advanced aspects of HTML injection is crucial for building and maintaining secure web applications, also checkout our previous blogs on xss attacks