CVE-2026-2728: LibreNMS Cross-Site Scripting Vulnerability in ShowConfigController
Summary
CVE-2026-2728: LibreNMS: Cross-Site Scripting in ShowConfigController. Affects librenms/librenms versions >= 25.12.0, < 26.3.0. Fixed in 26.3.0. How to fix ↓
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Background
LibreNMS is an open-source network monitoring tool that provides a comprehensive suite of features for monitoring network devices. It allows users to visualize network performance, manage alerts, and configure devices. However, a vulnerability exists in its RANCID Integration settings, which can lead to security risks if not addressed.
Vulnerability Detail
A Stored Cross-Site Scripting (XSS) vulnerability exists in the ShowConfig page of LibreNMS due to improper sanitization of the 'rancid_repo_url' configuration value. This vulnerability allows an authenticated user with permission to modify external settings to inject malicious JavaScript. When other users view the affected device pages, the injected script executes in their browsers, potentially leading to session hijacking or unauthorized data exposure. The vulnerability is introduced in the external settings configuration block, specifically at the settings/external/rancid endpoint.
How To Fix
Minimum fixed version
26.3.0
This is the first release that contains the fix.
composer require librenms/librenms:26.3.0Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, avoid using the RANCID Integration settings until the package is updated. If you must use it, ensure that only trusted administrators have access to modify the 'rancid_repo_url' configuration.
Conclusion
The CVE-2026-2728 vulnerability in LibreNMS presents a significant risk due to its potential for XSS attacks. It is crucial for administrators to update to the patched version to safeguard against exploitation. Regular monitoring and using tools like Vulert can help maintain the security of open-source applications.
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FAQ
The vulnerability is a Stored Cross-Site Scripting (XSS) issue that allows attackers to inject malicious scripts into the application.
Any user with administrative access to the LibreNMS application who can modify the RANCID Integration settings is affected.
The vulnerability can lead to session hijacking, unauthorized data exposure, and execution of arbitrary frontend code in the context of another administrator's session.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
The CVSS score of this vulnerability is 3.5, indicating a low severity level.
References
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