Denial of Service Vulnerability in Django URLField Implementation
Summary
CVE-2011-4137: The verify_exists functionality in the URLField implementation in Django before 1.2.7 and 1.3.x before 1.3.1 relies on Python libraries that attempt access to an arbitrary URL with no timeout, which allows remote attacke... Affects python-django versions < 1.3.1-1. Fixed in 1.3.1-1. How to fix ↓
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Background
Django is a high-level Python web framework that encourages rapid development and clean, pragmatic design. It is widely used for building web applications and provides a robust set of features, including an ORM, authentication, and URL routing. The vulnerability in question affects the URLField implementation, which is used to validate and store URLs in Django models. This vulnerability can lead to denial of service (DoS) attacks, impacting the availability of applications built with Django.
Vulnerability Detail
The vulnerability, identified as CVE-2011-4137, arises from the verify_exists functionality in the URLField implementation of Django versions prior to 1.2.7 and 1.3.x before 1.3.1. It relies on Python libraries that access arbitrary URLs without a timeout, allowing remote attackers to exploit this by providing URLs that result in slow responses, completed TCP connections with no application data, or large amounts of application data. This can lead to resource exhaustion and denial of service for the affected application.
How To Fix
Minimum fixed version
1.3.1-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade python-djangoTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
If upgrading is not immediately possible, consider implementing a timeout for URL validation requests in your application code. This can be done by modifying the URLField's verify_exists method to include a timeout parameter when making requests.
Conclusion
CVE-2011-4137 is a significant vulnerability in Django that can lead to denial of service attacks. It is crucial for developers using affected versions to upgrade to at least version 1.3.1 to mitigate the risk. Additionally, implementing a timeout for URL validation requests can serve as a temporary workaround while planning for an upgrade.
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FAQ
CVE-2011-4137 is a vulnerability in Django's URLField implementation that can lead to denial of service attacks due to unbounded URL validation requests.
Django versions before 1.2.7 and 1.3.x before 1.3.1 are affected by this vulnerability.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
The vulnerability can lead to denial of service, causing your application to become unresponsive or slow due to resource exhaustion.
Yes, you can implement a timeout for URL validation requests in your application code as a temporary workaround.
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