CVE-2020-12494
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 · uneditedBeckhoff's TwinCAT RT network driver for Intel 8254x and 8255x is providing EtherCAT functionality. The driver implements real-time features. Except for Ethernet frames sent from real-time functionality, all other Ethernet frames sent through the driver are not padded if their payload is less than the minimum Ethernet frame size. Instead, arbitrary memory content is transmitted within in the padding bytes of the frame. Most likely this memory contains slices from previously transmitted or received frames. By this method, memory content is disclosed, however, an attacker can hardly control which memory content is affected. For example, the disclosure can be provoked with small sized ICMP echo requests sent to the device.
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 confidenceThe TwinCAT RT network driver for Intel 8254x/8255x NICs fails to pad Ethernet frames with payload below the minimum 64-byte frame size. Instead, the driver leaks arbitrary memory content (likely from previous frame buffers) into the padding bytes, enabling information disclosure through crafted small ICMP echo requests.
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 data<= 3.1.0.3603<= 3.1.0.3512<= 2.11.0.2120<= 3.1.0.3600<= 3.1.0.3500<= 2.11.0.2117CVSS 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
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
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 TwinCAT installationLook for Beckhoff TwinCAT software on the system. Check Program Files for Beckhoff folder or check Windows Services for TwinCAT-related services.Affected if TwinCAT software is present on the system
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Identify TwinCAT versionCheck the installed TwinCAT version through Beckhoff TwinCAT Build Information tool, or check the file version of TcRuntime.exe or other TwinCAT binaries in the installation directory.Affected if Installed version matches or is lower than any of the affected version ranges: 3.1.0.3603, 3.1.0.3512, 2.11.0.2120, 3.1.0.3600, 3.0.3500, or 2.11.0.2117
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Identify network adapter hardwareCheck Windows Device Manager for Intel 8254x or 8255x network adapters, or run 'ipconfig /all' to list network interfaces and note the adapter description.Affected if An Intel 8254x or 8255x NIC is present and in use
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Verify RT driver configurationOpen TwinCAT Engineering (Visual Studio plug-in or TwinCAT System Manager), navigate to the network adapter configuration, and check if TwinCAT RT (real-time) driver is bound to the Intel 8254x/8255x adapter.Affected if TwinCAT RT network driver is bound to an Intel 8254x/8255x NIC
The system is affected if TwinCAT is installed with a version within the affected ranges and a TwinCAT RT driver is bound to an Intel 8254x or 8255x network adapter, allowing information disclosure via crafted small ICMP packets.
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 Beckhoff vendor patch for TwinCAT RT driver; implement network segmentation to isolate affected devices; validate frame padding behavior post-patch.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-12494 — 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-2020-12494 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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