Server-Side Template Injection Template

Executive Summary:

This report addresses a critical security vulnerability known as Server-Side Template Injection within our application. Server-Side Template Injection occurs when untrusted user input is improperly handled and executed within server-side template engines, leading to arbitrary code execution, data leakage, or server compromise. This report aims to detail the vulnerability, its potential impact on our systems and users, and actionable recommendations for mitigation.

Description of the Vulnerability:

Server-Side Template Injection vulnerabilities arise when web applications dynamically generate content using template engines without proper input validation and sanitization. Attackers exploit these vulnerabilities by injecting malicious template code into user-controllable input fields, such as form parameters or URL query strings. When processed by the server-side template engine, this injected code executes within the server's context, enabling attackers to execute arbitrary commands, access sensitive data, or compromise the server.


The impact of Server-Side Template Injection vulnerabilities can be severe, leading to various security risks including server compromise, data breaches, or unauthorized access within our application. Attackers can exploit these vulnerabilities to execute arbitrary code, extract sensitive information, or escalate privileges, potentially resulting in financial loss, reputational damage, or legal consequences for our organization.


The likelihood of exploitation depends on various factors including the visibility of server-side template engines within our application, the security measures implemented to validate and sanitize user input, and the attacker's knowledge and motivation. However, given the prevalence of Server-Side Template Injection vulnerabilities in web applications and the potential impact on server security and data integrity, the risk associated with this vulnerability is significant if not properly mitigated.

Steps to Reproduce:

  1. Identify user-controllable input fields within our application that are processed by server-side template engines.
  2. Inject malicious template code into these input fields, such as {{77}} or ${77}, to execute arbitrary expressions or commands.
  3. Submit the manipulated input to the server and observe if the injected template code is executed within the server's context.
  4. Determine if sensitive data can be accessed, commands can be executed, or server resources can be compromised due to the Server-Side Template Injection vulnerability.

Recommendations for Developers:

  1. Implement Input Sanitization: Sanitize and validate user input before passing it to server-side template engines to prevent injection of malicious template code.
  2. Use Context-Sensitive Output Encoding: Encode output rendered by server-side template engines to prevent interpretation of user input as template code, mitigating the risk of Server-Side Template Injection.


Addressing Server-Side Template Injection vulnerabilities is critical to protecting against arbitrary code execution, data leakage, and server compromise within our application. By implementing input sanitization and output encoding mechanisms, we can mitigate the risks associated with Server-Side Template Injection and enhance the overall security posture of our systems.