CVE-2026-84191
Received Received - Intake

Stored XSS in LibreNMS VRF Display Pages via SNMP Polling

Publication date: 2026-09-01

Last updated on: 2026-09-01

Assigner: VulnCheck

Description
LibreNMS before 26.5.0 contains stored cross-site scripting vulnerabilities in VRF display pages where mplsVpnVrfDescription, vrf_name, and mplsVpnVrfRouteDistinguisher fields from SNMP polling are rendered without sanitization. Attackers controlling a monitored network device can inject arbitrary JavaScript through SNMP responses that executes in the browser of any user viewing VRF-related 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-2026-84191
EUVD
EUVD-2026-69028

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
librenms librenms to 26.5.0 (exc)

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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 26.5.0 has a stored cross-site scripting (XSS) vulnerability in VRF display pages. Fields like mplsVpnVrfDescription, vrf_name, and mplsVpnVrfRouteDistinguisher from SNMP polling are rendered without sanitization. Attackers controlling a monitored device can inject JavaScript via SNMP responses, which executes in browsers of users viewing VRF-related pages.

Detection Guidance

Check LibreNMS version with 'cd /opt/librenms && ./validate.php' to see if it is below 26.5.0. Inspect VRF display pages for unexpected JavaScript in mplsVpnVrfDescription, vrf_name, or mplsVpnVrfRouteDistinguisher fields.

Impact Analysis

This vulnerability allows attackers to inject malicious scripts into LibreNMS pages viewed by users. Potential impacts include session hijacking, account takeover, lateral movement within networks, or establishing persistent backdoors. Users viewing affected VRF pages may unknowingly execute attacker-controlled JavaScript.

Mitigation Strategies

Upgrade LibreNMS to version 26.5.0 or later immediately. If upgrading is not possible, disable SNMP polling for VRF fields or implement input sanitization for those fields in the affected PHP files.

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