In this long read post, we will be discussing the security vulnerability found in the Django web framework versions 3.2 before 3.2.21, 4.1 before 4.1.11, and 4.2 before 4.2.5. The vulnerability (CVE-2023-41164) is in the django.utils.encoding.uri_to_iri() function, which could lead to a potential Denial of Service (DoS) attack. The DoS attack can be performed by passing certain inputs which contain a very large number of Unicode characters.

Code Snippet

First, let's have a look at a basic snippet of the vulnerable function, django.utils.encoding.uri_to_iri():

from django.utils.encoding import uri_to_iri

def vulnerable_input(url: str) -> str:
    return uri_to_iri(url)

This function takes a URL as input and returns the Internationalized Resource Identifier (IRI) representation of the input URL.

Exploit Details

An attacker can create a specially crafted input containing a vast number of Unicode characters, resulting in repeated conversion attempts which cause excessive processing time and eventually leading to a denial of service.

Here are some of the relevant links that provide more information on the CVE-2023-41164 vulnerability:

1. Django Security Advisory:
2. National Vulnerability Database (NVD) Entry:


To mitigate this vulnerability, it is recommended to update your Django installation to one of the following fixed versions:

You can update Django using pip by running the following command

pip install --upgrade "django>=3.2.21,<3.3"  # For Django 3.2 users
pip install --upgrade "django>=4.1.11,<4.2"  # For Django 4.1 users
pip install --upgrade "django>=4.2.5,<4.3"  # For Django 4.2 users

After upgrading Django, the vulnerability in the uri_to_iri() function will be resolved.


CVE-2023-41164 is a serious security vulnerability that affects various versions of the Django web framework, specifically targeting the uri_to_iri() function. It can be exploited to launch a DoS attack against an application, causing service disruptions. It is crucial to update your Django installation to the fixed versions mentioned above to protect your application from this vulnerability.


Published on: 11/03/2023 05:15:29 UTC
Last modified on: 12/14/2023 10:15:07 UTC