CVE-2020-12494Network attack vector

Memory disclosure via uninitialized Ethernet frame padding

Published Jun 16, 2020 · Updated Aug 4, 2024

Information disclosure in Beckhoff TwinCAT RT Intel drivers allows remote attackers to read memory via short Ethernet frames. The Tcl8254x.sys and Tcl8255x.sys drivers transmit undersized frames without zeroing padding bytes, appending arbitrary kernel memory. An unauthenticated network peer can provoke responses with small ICMP echo requests, but cannot reliably control which remnants of prior traffic are returned.

CVSS severity5.3
Medium
EPSS probability1.01%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Beckhoff TwinCAT RT Intel drivers allows remote attackers to read memory via short Ethernet frames. The Tcl8254x.sys and Tcl8255x.sys drivers transmit undersized frames without zeroing padding bytes, appending arbitrary kernel memory. An unauthenticated network peer can provoke responses with small ICMP echo requests, but cannot reliably control which remnants of prior traffic are returned.

The record

CVE
CVE-2020-12494
Published
Jun 16, 2020
Updated
Aug 4, 2024
Vendor
Beckhoff Automation GmbH & Co. KG
Product
TwinCAT Driver for Intel 8255x
Classifications
CWE-459, T1040
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 16, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <=2.11.0.2117 for TwinCAT 2.11 2350
  2. Affected versionversion=unspecified <=3.1.0.3500 for TwinCAT 3.1 4024
  3. Affected versionversion=unspecified <=3.1.0.3600 for TwinCAT 3.1 4024

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Beckhoff Automation GmbH & Co. KG · TwinCAT Driver for Intel 8255xversion=unspecified <=2.11.0.2117 for TwinCAT 2.11 2350; version=unspecified <=3.1.0.3500 for TwinCAT 3.1 4024; version=unspecified <=3.1.0.3600 for TwinCAT 3.1 4024
Beckhoff Automation GmbH & Co. KG · TwinCAT Driver for Intel 8254xversion=unspecified <=2.11.0.2120 for TwinCAT 2.11 2350; version=unspecified <=3.1.0.3512 for TwinCAT 3.1 4022; version=unspecified <=3.1.0.3603 for TwinCAT 3.1 4024

Published CVSS scores

5.3CERT@VDECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-459Incomplete Cleanup
T1040Network Sniffing

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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