Filename coming from the request

Docs > Code Analysis > Static Analysis Rules > Filename coming from the request

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Metadata

ID: python-django/open-filename-from-request

Language: Python

Severity: Error

Category: Security

Description

Improper validation of input data, leading to potential data leaks. The path should be checked and validated before opening a file in order to prevent opening random files and leaking data.

Learn More

CWE-22: Improper Limitation of a Pathname to a Restricted Directory

Non-Compliant Code Examples

def download_file1(request):
    url = request.GET.get("filename")
    print(f"url of the file: {url}")
    file = open(url, "rb")

    with open(url) as f:
        pass
    pass


def download_file2(request):
    url = request.POST.get("filename")
    print(f"url of the file: {url}")
    file = open(url, "rb")

    with open(url) as f:
        pass
    pass

def download_file3(request):
    url = request.BLA.get("filename")
    print(f"url of the file: {url}")
    file = open(url, "rb")

    with open(url) as f:
        pass
    pass

Compliant Code Examples

import os

def download_file(request):
    url = request.GET.get("filename")

    if ".." in url:
        return

    sanitized_path = os.path.realpath(url, strict=True)

    print(f"url of the file: {url}")
    file = open(sanitized_path, "rb")

    with open(sanitized_path) as f:
        pass
    pass