CVE-2020-12739
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 in the Fanuc i Series CNC (0i-MD and 0i Mate-MD) could allow an unauthenticated, remote attacker to cause an affected CNC to become inaccessible to other devices.
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 confidenceA denial-of-service vulnerability in Fanuc i Series CNC systems (0i-MD and 0i Mate-MD) allows an unauthenticated remote attacker to send specially crafted network requests that cause the CNC to become unresponsive and inaccessible to other connected devices on the network.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE dataall versionsall versionsall versionsall versionsall versionsall versionsall versionsall versionsCVSS 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
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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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Identify the CNC system modelCheck the CNC system nameplate, system information screen, or documentation for the exact model number (Series 30i, 31i, 32i, 35i, 0i Model F, 0i Model F Plus, or Power Motion I Model A)Affected if The model matches any of the affected series listed in the CVE (30i, 31i, 32i B Plus, 32i Model A, 35i B, 0i Model F, 0i Model F Plus, Power Motion I Model A)
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Verify network connectivity is enabledCheck the CNC network configuration settings or physically inspect the Ethernet port for an active connection. On the CNC operator panel, navigate to network or Ethernet settings to confirm the interface is enabledAffected if The Ethernet or network interface is actively connected to a network (the attack requires network access to send malicious packets)
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Assess network accessibilityReview network infrastructure to determine if the CNC has an IP address reachable from network segments outside of a dedicated operational technology (OT) network. Check firewall rules, VLAN assignments, and router/access control configurationsAffected if The CNC is reachable from network segments other than a dedicated, isolated CNC network, or if there are no firewall rules restricting access to authorized hosts only
User is affected if they operate any of the listed Fanuc CNC models (30i, 31i, 32i, 35i, 0i, Power Motion I Model A) that are network-connected and accessible from network segments beyond a dedicated, isolated OT network with controlled access.
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 dataIsolate CNC systems on a dedicated network segment with firewall rules restricting access to authorized hosts only; contact Fanuc for available firmware updates or patches.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 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 $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-12739 — 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-2020-12739 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
- No spam, self-promotion, credentials, or personal data