---
id: "CVE-2026-75491"
page: "https://infrastack.ai/live/CVE-2026-75491"
kind: "vulnerability"
aliases: ["CVE-2026-75491"]
title: "Cudy TR3000 router: MQTT login bypass lets attackers run commands as root"
severity: "critical"
cvss: 9.2
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["cudy", "infrastructure", "iot", "mosquitto", "mqtt", "routers", "tr3000"]
not_affected_if: ["firmware-2.5.42-or-later"]
published_at: "2026-11-13T10:18:16+00:00"
first_seen_at: "2026-11-13T10:47:35+00:00"
updated_at: "2026-11-13T10:48:28+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-75491", "first_seen_at": "2026-11-13T10:47:35+00:00"}]
exploit_sources: []
---

# Cudy TR3000 router: MQTT login bypass lets attackers run commands as root

Link for people: https://infrastack.ai/live/CVE-2026-75491 (this .md is for agents)

Cudy TR3000 routers before 2.5.42 have a Mosquitto plugin that accepts unsigned JSON Web Tokens using the alg none setting. An attacker holding any Cudy-trusted client certificate can log in as the admin device on port 8883 and publish batch command requests that run as root.

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

## How to check

- Check the router firmware version in the admin interface; versions below `2.5.42` are in the affected range.
- Check whether the Mosquitto broker on port `8883` is reachable from the network.

## Fix

- Cudy TR3000: move to `2.5.42` or later.

## Timeline

- 2026-11-13T10:47:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-75491

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/cudy-tr3000-before-2.5.42-mqtt-jwt-authentication-bypass-via-alg-none-tokens

## From the sources

Cudy TR3000 before 2.5.42 contains an authentication bypass vulnerability in the Mosquitto plugin auth_plugin_jwt.so that accepts unsigned JWTs using alg none. Attackers holding any Cudy-trusted client certificate can authenticate as admincudydevice on port 8883 and publish batchcmd requests to execute commands as root.

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_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_