CVE-2019-14233: Django HTMLParser Vulnerability

Background

Django is a popular Python web framework that simplifies the development of web applications. It provides various features and tools for handling web requests, managing databases, and rendering dynamic content. This vulnerability affects Django versions 1.11.x, 2.1.x, and 2.2.x. The vulnerability arises due to the behavior of the underlying HTMLParser used by Django's django.utils.html.strip_tags function. Specifically, when evaluating certain inputs containing large sequences of nested incomplete HTML entities, the function becomes extremely slow.

Vulnerability Detail

The vulnerability in Django's HTMLParser can lead to significant performance issues when processing certain inputs. Attackers could potentially exploit this vulnerability to launch denial-of-service attacks by submitting specially crafted input that triggers the slow evaluation of strip_tags. This could result in resource exhaustion and impact the availability of the affected Django application. It is important to note that this vulnerability does not directly allow for remote code execution or unauthorized access to sensitive information.

pip install --upgrade "django==6.1.2"

Workaround

As a workaround, developers can manually implement a custom function to strip HTML tags from input, instead of relying on Django's strip_tags. Here is an example of a simple implementation in Python:

import re

def strip_tags(input_string):
    return re.sub('<[^<]+?>', '', input_string)

Conclusion

The Django HTMLParser vulnerability (CVE-2019-14233) can result in significant performance issues and potential denial-of-service attacks. It is crucial to upgrade Django to the fixed versions or implement the provided workaround to mitigate the risk. For further support and assistance in vulnerability remediation, please contact DevNack.com.

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