CVE-2026-10831
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA denial-of-service vulnerability exists in NPort devices because of improper access control on the command port. The command interface does not properly validate whether a sender is associated with a valid data port session before accepting break signal commands. A remote attacker with network access can send crafted requests to disrupt serial communication for an active user session.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceNPort serial-to-Ethernet devices have improper access control on the command port. The command interface fails to validate whether a sender is associated with a valid data port session before accepting break signal commands, allowing unauthenticated remote attackers to disrupt active serial communications.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- Authentication
- X
- User interaction
- None
- Scope
- X
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:L/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
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Confirm NPort device modelAccess the device web interface, console, or use network discovery to identify the exact model number of the serial-to-Ethernet deviceAffected if Device is any NPort serial-to-Ethernet model
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Determine firmware versionLog into the device admin interface or use SNMP/serial console to retrieve the current firmware version; compare against any official Moxa NPort firmware release notesAffected if Firmware version falls within an affected range (if known) or is unpatched
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Verify command port exposurePerform a network port scan (e.g., nmap) targeting the device to identify open ports; the command interface typically uses TCP ports 9666, 9667, or 9668; check if these ports are accessible from untrusted networksAffected if Command port is reachable from external/untrusted networks without firewall filtering
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Inspect session validation settingAccess device configuration menus under Network Settings or Serial Settings; look for options related to session validation, break signal validation, or command port authentication; determine if any validation is enforced before accepting break commandsAffected if Session validation is disabled or not enforced for break signal commands
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Review access control configurationCheck device access control lists, IP filtering, or trusted host settings to see if the command port accepts connections only from legitimate data port sourcesAffected if No IP-based or session-based access restrictions are configured for the command port
A user is affected if they have an exposed NPort device where the command port accepts unauthenticated break signals without validating an associated data port session.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataApply network segmentation or firewall rules to restrict access to the command port to trusted sources only; monitor for anomalous break signal patterns; apply vendor firmware patches when available.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-10831 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-10831 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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