Moxa MGate: Improper verification of firmware signatures
Summary
Moxa MGate protocol gateways do not properly verify the cryptographic authenticity of firmware images before installation. An attacker with high privileges and access to the firmware update interface can install a modified image, which may run unauthorized code, compromise device integrity and availability, and persist across later updates. Exploitation requires high privileges and access to the update interface, and no fix has been confirmed yet.
Affected
- MGate MB3170 Series, version 1.0 (CNA record)
- MGate MB3270 Series, version 1.0 (CNA record)
- Secondary sources report a broader scope, but this is unverified. Check the Moxa advisory for the affected-product table, which also lists other MGate series.
Fixed in
Unknown. No confirmed fix for CVE-2026-86326 at disclosure. Fixed firmware listed in the advisory is tied to CVE-2026-86325.
Workaround
- Follow the Moxa Security Hardening Guides for the MGate MB3000 and MGate 5000 Series.
- Obtain firmware only from official Moxa sources and verify file hashes before updating.
- Restrict access to management and firmware update interfaces.
- Keep gateways off the internet and segment OT networks.
- Monitor for unexpected firmware changes or reboots.
Exploitation
- No confirmed in-the-wild exploitation.
- No public proof-of-concept reported.
- Not listed in the CISA KEV catalog.
- CISA SSVC: exploitation none, not automatable, total technical impact.
- EPSS 0.00188 at last check.
Our recommendation
- Inventory MGate devices, models and firmware versions.
- Confirm whether each model is listed as affected in Moxa advisory MPSA-269540.
- Restrict management and firmware update access to a small set of trusted administrators.
- Ask Moxa Technical Support for a fix timeline.
- Recheck the Moxa advisory, NVD and CISA KEV in about two weeks.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Moxa Security Advisory MPSA-269540 www.moxa.com
- Vulners CVE record CVE-2026-86326 vulners.com
- SecurityOnline: Moxa MGate vulnerabilities securityonline.info
- TheHackerWire: CVE-2026-86326 www.thehackerwire.com
- OpenCVE: CVE-2026-86326 app.opencve.io
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 09:26.
Original description (NVD)
An improper verification of cryptographic signature vulnerability exists in protocol gateways because the device does not properly verify the cryptographic authenticity of firmware images before installation. An attacker with high privileges and access to the firmware update interface could provide a specially crafted or modified firmware image, causing it to be installed on the device. Successful exploitation could allow the attacker to execute unauthorized code, compromise the integrity and availability of the device, and persist malicious modifications across subsequent firmware updates.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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