Buffer Overflow Vulnerability in Python Packages: python2.7 and python3.9
Summary
DEBIAN-CVE-2021-3177: Python 3.x through 3.9.1 has a buffer overflow in PyCArg_repr in _ctypes/callproc.c, which may lead to remote code execution in certain Python applications that accept floating-point numbers as untrusted input, as demons... Affects python2.7 versions < 2.7.18-2. Fixed in 2.7.18-2. 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, python2.7 and python3.9, are implementations of the Python programming language. They are used in various applications for scripting, automation, data analysis, and web development. This vulnerability affects how these packages handle floating-point numbers, potentially leading to severe security risks.
Vulnerability Detail
Python 3.x through 3.9.1 has a buffer overflow in the PyCArg_repr function located in _ctypes/callproc.c. This vulnerability can lead to remote code execution in certain Python applications that accept untrusted floating-point input. An example of this is passing a 1e300 argument to c_double.from_param, which can exploit the unsafe use of sprintf, allowing attackers to execute arbitrary code.
How To Fix
Minimum fixed version
2.7.18-2
This is the first release that contains the fix.
sudo apt-get install --only-upgrade python2.7Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, avoid using untrusted floating-point inputs in applications that utilize the affected Python versions. Implement input validation to ensure that only safe and expected values are processed.
Conclusion
The buffer overflow vulnerability in Python packages python2.7 and python3.9 poses significant security risks, particularly in applications that handle untrusted floating-point inputs. It is crucial to update to the patched versions to mitigate these risks and ensure the security of your applications.
See every vulnerability recorded for python2.7 →
FAQ
A buffer overflow occurs when a program writes more data to a buffer than it can hold, potentially overwriting adjacent memory and leading to unpredictable behavior or security vulnerabilities.
An attacker can exploit this vulnerability by providing specially crafted floating-point numbers as input, which may lead to arbitrary code execution within the affected application.
The vulnerability affects Python 3.x versions up to and including 3.9.1, as well as Python 2.7 versions prior to the fixed release.
Yes, you can use Vulert, which monitors open-source vulnerabilities in your software. By uploading a manifest file like package-lock.json, you can check for vulnerabilities in real-time without needing to install any software.
If immediate updates are not possible, ensure that your applications do not accept untrusted floating-point inputs and implement strict input validation as a temporary measure.
References
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