Server Side Template Injection

Server Side Template Injection

By Rohit Gautam
Server Side Template Injection

Summary: Server-Side Template Injection (SSTI) is a critical web security vulnerability that occurs when user-supplied input is directly embedded in a server-side template engine, leading to the execution of arbitrary code. Exploiting this vulnerability enables an attacker to execute commands, access sensitive information, or perform unauthorized actions on the server.

Severity: High

Attack Vector: Remote

Complexity: High

Impact: By exploiting SSTI, an attacker can execute arbitrary code within the server-side template, potentially leading to unauthorized access to sensitive data, remote code execution, or even a complete compromise of the server and its resources.

Affected IP Address:

Port: 443

Steps to Reproduce:

1. Identify a target system that is susceptible to Server-Side Template Injection.
2. Determine the injection points within the server-side template engine where user-supplied input is incorporated.
3. Craft a malicious payload that includes template engine-specific syntax and commands to execute arbitrary code.
4. Submit the payload as part of the user input or as a parameter to the vulnerable template engine.
5. Observe the response to confirm the successful execution of the injected code or command.


To mitigate Server-Side Template Injection vulnerabilities, it is crucial to implement the following measures:
1. Avoid direct embedding of user input within server-side templates.
2. Implement strict input validation and sanitization to prevent the injection of template engine-specific syntax.
3. Apply proper context-specific output encoding to prevent template injection attacks.
4. Utilize template engine-specific security features and features that provide sandboxing or restricted execution environments.
5. Regularly update and patch both the web application and the template engine to address any known vulnerabilities.


1. OWASP - Server-Side Template Injection:
2. PortSwigger - Server-Side Template Injection:

Proof of Concept:

Please refer to the attached screenshot or video for a visual demonstration of a Server-Side Template Injection attack.