Critical Vulnerability in Python 3.8 and 3.9: IP Address Handling Flaw
Summary
UBUNTU-CVE-2021-29921: In Python before 3,9,5, the ipaddress library mishandles leading zero characters in the octets of an IP address string. Affects python3.8 versions < 3.8.0-3ubuntu1~18.04.2+esm2. Fixed in 3.8.0-3ubuntu1~18.04.2+esm2. How to fix ↓
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Background
Python is a widely-used high-level programming language known for its readability and versatility. The affected packages, python3.8 and python3.9, are implementations of Python 3 for Ubuntu systems. They provide essential libraries and tools for developers to build applications. However, a vulnerability in the ipaddress library of these versions can lead to security risks, particularly in applications that rely on IP address validation.
Vulnerability Detail
In Python versions prior to 3.9.5, the ipaddress library mishandles leading zero characters in the octets of an IP address string. This flaw can allow attackers to bypass access control mechanisms that depend on IP address validation, potentially leading to unauthorized access to sensitive resources. The vulnerability is classified with a CVSS score of 9.8, indicating a critical level of severity.
How To Fix
Minimum fixed version
3.8.0-3ubuntu1~18.04.2+esm2
This is the first release that contains the fix.
sudo apt-get install --only-upgrade python3.8Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, consider implementing additional validation checks in your application to handle IP addresses correctly, ensuring that leading zeros are not accepted. This can be done by using regular expressions to validate the format of IP addresses before processing them.
Conclusion
The vulnerability in Python's ipaddress library poses significant security risks, particularly for applications relying on IP address validation. It is crucial to update to the patched versions of Python 3.8 and 3.9 to mitigate these risks. Additionally, utilizing tools like Vulert can help monitor and manage vulnerabilities effectively.
See every vulnerability recorded for python3.8 →
FAQ
The vulnerability allows attackers to bypass IP address-based access controls due to improper handling of leading zeros in IP address strings.
Python versions prior to 3.9.5 and 3.8.10 are affected by this vulnerability.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in real-time. Check your application using the Vulert playground at Vulert Scanner.
The CVSS score of this vulnerability is 9.8, indicating a critical severity level.
If immediate updates are not possible, implement additional validation checks for IP addresses in your application as a temporary workaround.
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