CVE-2026-84192
Received Received - Intake

Stored XSS in LibreNMS via SNMP and Syslog Data

Publication date: 2026-09-01

Last updated on: 2026-09-01

Assigner: VulnCheck

Description
LibreNMS before 26.3.1 contains a stored cross-site scripting vulnerability in legacy PHP templates that output SNMP-sourced and syslog-sourced data without escaping. An attacker who controls a monitored network device can inject arbitrary JavaScript through SNMP interface descriptions or syslog program fields that executes when authenticated users view affected pages.

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Meta Information

Published
2026-09-01
Last Modified
2026-09-01
Generated
2026-09-01
AI Q&A
2026-09-01
EPSS Evaluated
N/A
NVD
CVE-2026-84192
EUVD
EUVD-2026-69029

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
librenms librenms to 26.3.1 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

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Executive Summary

LibreNMS before version 26.3.1 has a stored cross-site scripting (XSS) vulnerability in legacy PHP templates. It occurs because SNMP-sourced and syslog-sourced data is output without proper escaping. An attacker who controls a monitored device can inject malicious JavaScript through fields like SNMP interface descriptions or syslog program fields. This script executes when authenticated users view affected pages in LibreNMS.

Detection Guidance

Check LibreNMS version with 'php -r "include(\"includes\/common.inc.php\"); echo $config['version'];". If version is below 26.3.1, the system is vulnerable. Inspect SNMP interface descriptions and syslog program fields for unusual JavaScript content or HTML tags.

Impact Analysis

This vulnerability allows an attacker to inject malicious JavaScript that executes when users view affected pages. This could lead to session hijacking, theft of sensitive data, or unauthorized actions performed on behalf of the user. Attackers need network access and user interaction to exploit it.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, potentially violating GDPR and HIPAA compliance requirements. It may result in data breaches, unauthorized disclosure of personal or health information, and failure to maintain data integrity and confidentiality.

Mitigation Strategies

Upgrade LibreNMS to version 26.3.1 or later immediately. Review and sanitize SNMP interface descriptions and syslog program fields for malicious content. Implement network segmentation to limit access to LibreNMS.

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