CVE-2021-32052: Header injection possible in Django

Background

Django is a popular Python web framework that provides a set of tools and libraries for building web applications. It is widely used due to its simplicity, scalability, and security features. However, a vulnerability has been discovered in versions 2.2 before 2.2.22, 3.1 before 3.1.10, and 3.2 before 3.2.2 (with Python 3.9.5+), which allows for header injection. This vulnerability can be exploited if an application uses values with newlines in an HTTP response. It is important to note that Django itself is unaffected because HttpResponse prohibits newlines in HTTP headers.

Vulnerability Detail

The vulnerability in Django allows for header injection, which occurs when an attacker is able to inject malicious content into the headers of an HTTP response. This can lead to various security risks, such as cross-site scripting (XSS) attacks, cache poisoning, and session hijacking. The URLValidator in affected versions of Django does not prohibit newlines and tabs, except when the URLField form field is used. This oversight enables an attacker to inject newlines into the headers, potentially allowing them to manipulate the response or inject additional headers.

pip install --upgrade "django==6.1.2"

Workaround

If upgrading to the fixed versions is not immediately possible, a temporary workaround can be implemented by manually validating and sanitizing the input values to ensure they do not contain newlines or tabs. This can be done by implementing custom validation logic or using a library that provides secure URL validation. Here is an example of how to sanitize the input using Python's re module:

import re

def sanitize_input(url):
    sanitized_url = re.sub(r'[
	]', '', url)
    return sanitized_url

Conclusion

The header injection vulnerability in Django can have serious security implications, allowing attackers to manipulate HTTP responses and potentially compromise the application. It is crucial to upgrade to the latest patched versions of Django (2.2.22, 3.1.10, or 3.2.2) to mitigate this vulnerability. If immediate upgrading is not possible, implementing a workaround to sanitize input values can provide temporary protection. For further assistance and support in vulnerability remediation, please contact DevNack.com.

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