CVE-2024-56363

Jinja2 template injection allows arbitrary code execution via unsanitized user input.

• CVSS 7.8
• CWE-97
• Input Validation and Sanitization
• Remote

APTRS (Automated Penetration Testing Reporting System) is a Python and Django-based automated reporting tool designed for penetration testers and security organizations. In 1.0, there is a vulnerability in the web application's handling of user-supplied input that is incorporated into a Jinja2 template. Specifically, when user input is improperly sanitized or validated, an attacker can inject Jinja2 syntax into the template, causing the server to execute arbitrary code. For example, an attacker might be able to inject expressions like {{ config }}, {{ self.class.mro[1].subclasses() }}, or more dangerous payloads that trigger execution of arbitrary Python code. The vulnerability can be reproduced by submitting crafted input to all the template fields handled by ckeditor, that are passed directly to a Jinja2 template. If the input is rendered without sufficient sanitization, it results in the execution of malicious Jinja2 code on the server.

CVE

CVE-2024-56363

CWE

CWE-97

CVSS base score

7.8

Published

2024-12-23

OWASP

A03 Injection

Orthogonal defect classification

Interface

Code defect classification

Incorrect Functionality

Category

Input Validation and Sanitization

Subcategory

Insecure Parsing or Deserialization

Accessibility scope

Remote

Impact

Arbitrary Code Execution

Affected component

APTRS

Solution

Upgrade to APTRS 1.1 or later.

from flask import Flask, render_template, request
from jinja2 import Environment, FileSystemLoader

app = Flask(__name__)
template_env = Environment(loader=FileSystemLoader('.'))


@app.route('/', methods=['GET', 'POST'])
def index():
    # VULNERABLE: This code is susceptible to command injection
    if request.method == 'POST':
        user_input = request.form.get('content', '')
        
        template = template_env.from_string(f"<div>{user_input}</div>")
        rendered_html = template.render()
        
        return f'<h1>Rendered Content:</h1> {rendered_html}'
    
    return '''
        <form method="post">
            <textarea name="content"></textarea>
            <button type="submit">Render</button>
        </form>
    '''


if __name__ == '__main__':
    app.run()

from flask import Flask, render_template, request
from jinja2 import Environment, FileSystemLoader

app = Flask(__name__)
template_env = Environment(loader=FileSystemLoader('.'))

@app.route('/', methods=['GET', 'POST'])
def index():
    # SECURE: This version prevents command injection
    if request.method == 'POST':
        user_input = request.form.get('content', '')
        
        template = template_env.from_string(f"<div>{{{{ {user_input} }}}}</div>")
        rendered_html = template.render()
        
        return f'<h1>Rendered Content:</h1> {rendered_html}'
    
    return '''
        <form method="post">
            <textarea name="content"></textarea>
            <button type="submit">Render</button>
        </form>
    '''


if __name__ == '__main__':
    app.run()

{{ self.class.mro[1].subclasses()[122].__init__.__globals__['os'].popen('whoami').read() }}

@misc{vaitp:cve202456363,
  title        = {{Jinja2 template injection allows arbitrary code execution via unsanitized user input.
}},
  author       = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
  year         = {2024},
  note         = {VAITP Python Vulnerability Dataset, entry CVE-2024-56363},
  howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2024-56363/}}
}