Python JSON Logger is a JSON formatter for Python logging, which makes it easier for developers to integrate logs into their applications. The package provides a more standardized format for log messages and allows developers to customize the log outputs. However, between 30 December 2024 and 4 March 2025, Python JSON Logger was found to be vulnerable to Remote Code Execution (RCE) attacks due to a missing dependency in its source code. The vulnerability was introduced because the msgspec-python313-pre package was deleted by its owner, leaving the name open for potential malicious reuse. This article aims to provide a detailed explanation of the vulnerability, its exploit details, and links to original references. We will also provide examples and code snippets to better understand the issue.

Background and Details

During the mentioned timeframe, a malicious package could have been published under the same name (msgspec-python313-pre) which would allow any attacker to gain RCE upon any Python JSON Logger user running Python 3.13 who installed the development dependencies by executing the following command:

pip install python-json-logger[dev]

As a result, any application utilizing Python JSON Logger on Python 3.13 would potentially be vulnerable to RCE. An attacker could exploit this vulnerability by creating a package with a malicious payload that gets executed whenever the user installs the development dependencies.

Resolution

The vulnerability has since been patched in version 3.3.. Developers using Python JSON Logger on Python 3.13 are advised to update their package by running:

pip install python-json-logger --upgrade

To help mitigate such risks in the future, developers should carefully review their dependencies and ensure that package names are accurate and trustworthy. Additionally, package owners should consider publishing a new package with a different name if a previous package has been deleted to avoid potential confusion or exploitation.

For further information about this vulnerability, please refer to the following sources

1. Python JSON Logger GitHub Repository: https://github.com/madzak/python-json-logger
2. Python JSON Logger PyPI Package: https://pypi.org/project/python-json-logger/
3. CVE-2025-27607: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2025-27607

Conclusion

The CVE-2025-27607 vulnerability in Python JSON Logger demonstrates how dependency management can pose significant security risks for software applications. Developers should always consider the potential impact that dependencies can have on their projects to help minimize these risks. By staying informed and vigilant about potential security vulnerabilities, developers can better protect their applications and systems from potential threats.

Timeline

Published on: 03/07/2025 17:15:22 UTC
Last modified on: 03/07/2025 18:15:48 UTC