What’s Vulnerable › Vulnerabilities

CVE-2020-12494: Beckhoff: Etherleak in TwinCAT RT network driver

• Severity: medium (CVSS 5.0 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-06-16 · updated 2026-06-17
• Weakness: CWE-459

Description

Beckhoff'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.

Affected products

• ICS-CERT Beckhoff TwinCAT: through 3.1.0.3512; through 2.11.0.2120; through 3.1.0.3600; through 3.1.0.3500; through 2.11.0.2117
• Beckhoff Twincat Driver: through 3.1.0.3603

References

• https://cert.vde.com/en-us/advisories/vde-2020-019
• https://cert.vde.com/en-us/advisories/vde-2020-019

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