# CVE-2026-84409 — Lantronix G520 Series

> As of 2026-09-30, CVE-2026-84409 is a HIGH-severity vulnerability in Lantronix G520 Series, CVSS v3.1 7.5. No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-84409 as of 2026-09-30; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-09-30

## What is CVE-2026-84409?

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.

The record classifies CVE-2026-84409 under weakness class [CWE-79](https://intel.threadlinqs.com/cwe/CWE-79). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 6 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.5 — HIGH (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **CVSS v4.0 base score:** 7.7 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 3.8/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-29, last modified 2026-09-30

## Is CVE-2026-84409 being exploited?

It currently carries a trending score of 30 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **Lantronix**: G520 Series

## How to fix CVE-2026-84409

No vendor patch reference has been recorded for CVE-2026-84409 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-84409

No threat campaign in the Threadlinqs corpus currently references CVE-2026-84409, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org. Last verified by Threadlinqs on 2026-09-30.

**Other references**

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

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-84409
Full detection coverage and IOCs for threats exploiting CVE-2026-84409 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp