CVE-2016-4000: Jython insecure deserialization in PyFunction object

CVE-2016-4000 · Severity: critical · CVSS 9.8 · Published 2022-05-13

Jython, a Java implementation of the Python programming language, is vulnerable to a flaw that allows remote attackers to execute malicious code. By sending specially crafted data to an application using Jython, an attacker could gain full control over the affected system. This could lead to data theft, service disruption, or unauthorized access to internal corporate resources.

Vendors: Maven, Python Software Foundation.

Quick answers

Is CVE-2016-4000 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2016-4000 being exploited in the wild.
How severe is CVE-2016-4000?
Critical severity, with a CVSS score of 9.8, published 13 May 2022.
Which products and versions are affected?
org.python:jython (Maven) < 2.7.1b3, ECOSYSTEM:introduced=0,fixed=2.7.1b3; org.python:jython-standalone (Maven) < 2.7.1b3, ECOSYSTEM:introduced=0,fixed=2.7.1b3; Python Software Foundation Jython < 2.7.1b3.
Is there a fix for CVE-2016-4000?
Yes. org.python:jython (Maven): upgrade to 2.7.1b3 or later; org.python:jython-standalone (Maven): upgrade to 2.7.1b3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2016-4000 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2016-4000?
Check whether you run org.python:jython (Maven), org.python:jython-standalone (Maven), Python Software Foundation Jython or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • org.python:jython (Maven): upgrade to 2.7.1b3 or later
    # set org.python:jython to 2.7.1b3 in your pom.xml or build.gradle
  • org.python:jython-standalone (Maven): upgrade to 2.7.1b3 or later
    # set org.python:jython-standalone to 2.7.1b3 in your pom.xml or build.gradle

Technical details

A deserialization vulnerability exists in Jython versions prior to 2.7.1b3. The root cause is the insecure handling of untrusted data when reconstructing 'PyFunction' objects from a serialized state. A remote, unauthenticated attacker can exploit this by sending a specially crafted serialized object over the network to an application that uses Jython for processing. Successful exploitation allows for arbitrary code execution (RCE) in the context of the application. The issue is addressed in version 2.7.1b3.

Affected products

  • Python Software Foundation jython < 2.7.1b3
  • Python Software Foundation jython-standalone < 2.7.1b3

Identifiers

  • CVE-2016-4000
  • GHSA-6r7r-jj8h-pq6v

Timeline

  • 2017-07-06: advisory: NVD published the vulnerability details
  • 2022-05-13: advisory: GitHub Advisory Database entry published

References

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