---
id: "CVE-2026-43844"
kind: "vulnerability"
aliases: ["CVE-2026-43844"]
title: "Unnamed proprietary protocol lets attackers bypass authentication entirely"
severity: "critical"
cvss: 9.3
epss: null
exploited: false
status: "open"
category: "other"
products: [{"name": "ADAM-3600 EdgeLink", "fixed": ["2.8.5.0"], "affected": "< 2.8.5.0", "ecosystem": "vendor"}]
ecosystems: []
tags: ["adam-3600", "advantech", "authentication-bypass", "edgelink", "ics", "ot", "other", "rtu", "unknown"]
not_affected_if: ["firmware-2.8.5.0-or-later", "not-network-reachable"]
published_at: "2026-10-20T09:17:10+00:00"
first_seen_at: "2026-10-23T21:57:20+00:00"
updated_at: "2026-10-23T23:22:24+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43844", "first_seen_at": "2026-10-23T21:57:20+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-23T23:22:24+00:00"}]
---

# Unnamed proprietary protocol lets attackers bypass authentication entirely

Advantech ADAM-3600 EdgeLink remote terminal unit (industrial data acquisition) has an authentication bypass on its proprietary protocol, CVSS 4.0 9.3, network reachable, no privileges needed. Vendor says the cause is a singleton pattern that mixes up commands between TCP ports 6001 and 7001, which differ in what they implement. Found by Nozomi Networks (Simone Bossi, Raffaele Bova). Disclosed to vendor 2026-04-29, patched 2026-10-15, public 2026-10-20. Not known to be exploited.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:ADAM-3600 EdgeLink affected < 2.8.5.0 fixed 2.8.5.0

## How to check

Check the EdgeLink image version on each ADAM-3600 (device web UI or firmware info). Anything before 2.8.5.0 is affected. Also check whether TCP ports 6001 and 7001 are reachable from untrusted networks, for example with nmap -p 6001,7001 <device>.

## Fix

Update ADAM-3600 EdgeLink firmware to 2.8.5.0 or later (Advantech support page, ADAM-3600-C2G EdgeLink Image). Until then, keep the device off the internet and firewall ports 6001/7001 and the web interface to trusted hosts. Note: the Advantech firmware page I saw listed 2.8.5.0 as Beta, so confirm the release channel.

## Timeline

- 2026-10-23T21:57:20+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-43844
- 2026-10-23T23:22:24+00:00 analyst — Advantech ADAM-3600 EdgeLink RTU, one of 30 CVEs in ACIRT-261001 (item 16, NN-2026-0005); fixed in 2.8.5.0. Read vendor PDF + CSA SG alert. No exploitation or public PoC found; X not searched (ICS, low chatter). Advisory lists no public workaround beyond network restriction.

## Documents

- [advisory] Advantech: Vulnerabilities Identified in ADAM-3600 (ACIRT-261001) https://advcloudfiles.advantech.com/cms/de8e2d94-10ab-470e-ac6f-d2e5434f4ec4/Security%20Advisory%20PDF%20File/SECURITY-ADVISORY----ADAM-3600.pdf
- [describes] CSA Singapore AL-2026-149: Advantech ADAM-3600 EdgeLink multiple vulnerabilities https://www.csa.gov.sg/alerts-and-advisories/alerts/al-2026-149
- [mentions] CVE Record CVE-2026-43844 https://www.cve.org/CVERecord?id=CVE-2026-43844

## From the sources

A vulnerability in the proprietary protocol could allow an attacker to bypass the authentication mechanism.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_