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SSTI (Server-Side Template Injection)

Vulnerability Name

Server-side template injection on [Parameter] in [Module/Functionality]

Vulnerability Description

Server-side template injection is when an attacker is able to use native template syntax to inject a malicious payload into a template, which is then executed server-side. This allows attackers to inject arbitrary template directives in order to manipulate the template engine, often enabling them to take complete control of the server.

As the name suggests, server-side template injection payloads are delivered and evaluated server-side, potentially making them much more dangerous than a typical client-side template injection.

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Steps to Reproduce

  1. Go to [Affected URL].
  2. Intercept the request in burp suite and send it to repeater.
  3. Change the value of [Vulnerable Parameter] to the above payload and send the request.
  4. Observe as the payload executes in the response.


Modify the steps to reproduce above if required. Attach snapshots (POC) or a video link here.


At the severe end of the scale, an attacker can potentially achieve remote code execution, taking full control of the back-end server and using it to perform other attacks on internal infrastructure.

Even in cases where full remote code execution is not possible, an attacker can often still use server-side template injection as the basis for numerous other attacks, potentially gaining read access to sensitive data and arbitrary files on the server.

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  • One of the simplest ways to avoid introducing server-side template injection vulnerabilities is to always use a "logic-less" template engine, such as Mustache, unless absolutely necessary.
  • Separating the logic from the presentation as much as possible can greatly reduce your exposure to the most dangerous template-based attacks.
  • Another measure is to only execute users' code in a sandboxed environment where potentially dangerous modules and functions have been removed altogether.

Add your specific remediation if required, the above is a general remediation.