CVE-2021-25933: Cross-site Scripting in OpenNMS Horizon
Summary
CVE-2021-25933: Cross-site Scripting in OpenNMS Horizon. Affects org.opennms:opennms versions >= 1.0.0, < 27.1.1. Fixed in 27.1.1. How to fix ↓
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Background
OpenNMS Horizon is an open-source network management platform that provides fault and performance management capabilities. It is widely used by organizations to monitor and manage their network infrastructure. However, versions opennms-1-0-stable through opennms-27.1.1 of OpenNMS Horizon are vulnerable to a stored cross-site scripting (XSS) attack. This vulnerability allows an authenticated attacker to inject arbitrary script into the application, potentially leading to the execution of malicious code on the client-side. The vulnerable function validateFormInput() fails to properly validate the groupName and groupComment parameters, enabling the attacker to trick other admin users into downloading malicious files.
Vulnerability Detail
The stored cross-site scripting vulnerability in OpenNMS Horizon can have severe consequences for organizations using the platform. An authenticated attacker can exploit this vulnerability to inject malicious script into the application, which can be executed by unsuspecting admin users. This can lead to various attacks, including the theft of sensitive information, session hijacking, and the installation of malware or ransomware. The impact of this vulnerability depends on the privileges of the targeted admin user and the actions they can perform within the application. The vulnerability has a CVSS score of 4.8, indicating a moderate severity level.
How To Fix
Latest published version: 31.0.3 as of 22 Oct 2026
Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
27.1.1
This is the first release that contains the fix.
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Workaround
As a temporary workaround, organizations can implement a Content Security Policy (CSP) to mitigate the risk of XSS attacks. A CSP allows administrators to define a whitelist of trusted sources for content, preventing the execution of scripts from untrusted sources. By configuring a strict CSP, organizations can limit the impact of the vulnerability until a proper fix can be applied. Here is an example of a Content Security Policy header that can be added to the application's HTTP response:
Content-Security-Policy: default-src 'self'; script-src 'self' 'unsafe-inline';
Conclusion
The stored cross-site scripting vulnerability in OpenNMS Horizon poses a significant risk to organizations using the affected versions. It is crucial to promptly update to a non-vulnerable version and implement proper input validation mechanisms to prevent the execution of arbitrary scripts. Additionally, organizations can apply a Content Security Policy (CSP) as a temporary workaround. For further assistance and support in addressing this vulnerability, please contact DevNack.com.
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FAQ
The vulnerability allows an authenticated attacker to inject arbitrary script into the OpenNMS Horizon application, potentially leading to the execution of malicious code on the client-side. This can result in various attacks, including data theft, session hijacking, and the installation of malware or ransomware.
Organizations using OpenNMS Horizon versions opennms-1-0-stable through opennms-27.1.1 are affected by this vulnerability. It is important for these organizations to update to a non-vulnerable version and apply the necessary fixes.
To mitigate the risk of this vulnerability, it is recommended to upgrade to a non-vulnerable version of OpenNMS Horizon and implement proper input validation and sanitization mechanisms. Additionally, organizations can implement a Content Security Policy (CSP) as a temporary workaround.
At the time of this advisory, there are no known public exploits specifically targeting this vulnerability. However, it is important to apply the necessary fixes and security patches to prevent potential exploitation.
For more information about this vulnerability, you can refer to the official advisory published by OpenNMS or consult with security experts and community forums dedicated to OpenNMS Horizon.
References
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