Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS
CVE-2026-75491 Overview
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.
Critical Impact
Affected Products
- Cudy TR3000: see the vendor advisory for the exact affected versions
Discovery Timeline
- 2026-11-13: CVE-2026-75491 published to the National Vulnerability Database by disclosure@vulncheck.com
- 2026-11-13: last updated in the NVD database
Technical Details for CVE-2026-75491
Vulnerability Analysis
CVE-2026-75491 is a Security Vulnerability weakness (CWE-347) in Cudy TR3000. Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction.
With a CVSS base score of 9.2 and an EPSS exploitation probability of 0.25 percent, apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Root Cause
The vendor description states: 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.
Attack Vector
Based on the CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Attack complexity is high complexity.
No exploitation in the wild is confirmed by CISA at the time of the last update. Check the references below for any vendor or researcher proof of concept.
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Detection Methods for CVE-2026-75491
Detection Strategies
- Inventory every instance of Cudy TR3000 and compare the running version with the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Run an authenticated vulnerability scan once your scanner ships a check for this CVE.
Monitoring Recommendations
- Forward Cudy TR3000 application, access and audit logs to your SIEM for retrospective hunting.
- Alert on new processes, configuration changes or outbound connections from the affected service.
- Track the vendor advisory and the CISA KEV catalog for changes in exploitation status.
How to Mitigate CVE-2026-75491
Immediate Actions Required
- Apply the fixed version of Cudy TR3000 named in the vendor advisory.
- Prioritize internet facing and business critical instances first.
- Rescan after the change to confirm the exposure is closed.
Patch Information
Use the fixed version listed in the vendor advisory for Cudy TR3000.
Workarounds
- If patching must wait, restrict network access to the affected service and place it behind authentication or a web application firewall rule.
CWE References
Technical References
This entry is built directly from NVD, CISA KEV and EPSS data. Verify fixed versions in the vendor advisory before you deploy.
Frequently asked questions
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