Understanding the Impact and Resolution of CVE-2018-20406 on Python

Welcome to our in-depth look at CVE-2018-20406, a significant security issue in the Python programming language, specifically affecting its _pickle.c module. This analysis aims to provide you, our readers at LinuxPatch, with detailed insights into the vulnerability's specifics, the risks it poses, and how to mitigate them effectively.

What is CVE-2018-20406?

CVE-2018-20406 is a high-severity vulnerability identified in the Python programming language's pickle module, which is used for serializing and deserializing Python object structures. An integer overflow can occur via a large LONG_BINPUT value during the resize operation, potentially resulting in memory exhaustion. This flaw is particularly critical if the pickle format is employed for handling large data volumes, reaching tens or hundreds of gigabytes.

Impact of CVE-2018-20406

This vulnerability, indexed with a severity score of 7.5, could facilitate a denial of service through memory exhaustion. The security flaw impacts various versions of Python up to and including 3.6.6. It highlights the risks associated with handling serialized data, especially when it involves large-scale data structures.

Affected Python Versions

The versions impacted include Python versions prior to 3.7.1, spanning multiple sub-releases in the 3.4.x, 3.5.x, 3.6.x, and early 3.7.x series. The Python team addressed the issue adequately in later releases starting from Python 3.7.1 and its preceding release candidates, among others.


To address CVE-2018-20406, patches were applied across multiple Python versions. Users and developers are strongly advised to upgrade to Python 3.7.1 or newer to ensure they are protected against this vulnerability. As always, maintaining software and ensuring it stays up to date is crucial in protecting against potential threats.

Preventive Measures

Apart from upgrading Python to a secure version that contains the necessary patches for this vulnerability, users and developers should consider additional security practices:

  • Audit your environment for vulnerable versions of Python.
  • Limit the use of object serialization, especially with untrusted data.
  • Implement security checks or layers that can detect and mitigate abnormal behavior stemming from serialized data.

Understanding and mitigating the impacts of vulnerabilities like CVE-2018-20406 is critical for maintaining the security integrity of your applications and systems. If you're looking for dedicated tools to manage Python patches automatically on your Linux servers, consider visiting LinuxPatch, our comprehensive patch management platform. It can help secure your environments against vulnerabilities by ensuring that you are always using the most up-to-date and secure versions of software.

Stay safe, stay updated, and remember that the best defense against threats is a proactive approach to cybersecurity.