A recently discovered vulnerability, identified as CVE-2023-39000, involves a reflected cross-site scripting (XSS) issue that affects the /ui/diagnostics/log/core/ component of OPNsense versions before 23.7. This vulnerability could enable attackers to maliciously inject arbitrary JavaScript into the targeted system via the URL path, potentially leading to various consequences such as unauthorized data extraction or modification, and compromised user accounts.


OPNsense is an open-source firewall and routing platform that is widely used for its extensive security features and high-performance capabilities. The platform is based on FreeBSD and is designed to be a versatile solution for securing networks and managing network traffic. Despite its many advantages, the recent discovery of this vulnerability, CVE-2023-39000, has raised concerns among users and administrators.

Details of the Vulnerability

In OPNsense versions before 23.7, the /ui/diagnostics/log/core/ component fails to properly sanitize user input, allowing attackers to exploit the reflected XSS vulnerability. When this input is subsequently processed and returned to the user's browser, the malicious script embedded by the attacker is executed. This contextually-based attack has the potential to cause harm through the execution of unauthorized actions or extraction of sensitive information.

Here's a sample code snippet that demonstrates how an attacker could exploit this vulnerability


In this example, the attacker would replace evil_js_code_here with their malicious JavaScript code, while <OPNsense_IP> would be the IP address of the target OPNsense installation.

For more details and information, please refer to the following official sources

- National Vulnerability Database (NVD) entry:
- OPNsense Security Advisory:

Exploit Details

Currently, there are no known instances of this vulnerability being exploited in the wild. However, given the public nature of this issue and the distribution of information through multiple sources, it is advised that users and administrators take immediate steps to mitigate the risk of exploitation.

Mitigation Recommendations

To protect against this vulnerability, it is strongly recommended that users and administrators running OPNsense versions before 23.7 immediately upgrade to the latest version, which can be downloaded from Additionally, users should follow best practices for securing their installations, including the use of strong authentication methods and encryption where applicable. Regular security audits and updates should also be conducted to ensure the ongoing security of the system.


CVE-2023-39000 is a critical reflected XSS vulnerability that affects the /ui/diagnostics/log/core/ component of OPNsense before version 23.7. It allows attackers to inject arbitrary JavaScript via the URL path, potentially leading to various security implications, including unauthorized data extraction or modification. To prevent exploitation, users and administrators should immediately upgrade their OPNsense installations to the most recent version and conduct regular security audits to ensure the protection of their networks.


Published on: 08/09/2023 19:15:00 UTC
Last modified on: 08/15/2023 15:08:00 UTC