What’s Vulnerable › Vulnerabilities

CVE-2020-12526: BECKHOFF: DoS-Vulnerability for TwinCAT OPC UA Server and IPC Diagnostics UA Server

• Severity: medium (CVSS 5.3 v3.1)
• 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: 2021-05-13 · updated 2026-06-17
• Weakness: CWE-20

Description

TwinCAT OPC UA Server in versions up to 2.3.0.12 and IPC Diagnostics UA Server in versions up to 3.1.0.1 from Beckhoff Automation GmbH & Co. KG are vulnerable to denial of service attacks. The attacker needs to send several specifically crafted requests to the running OPC UA server. After some of these requests the OPC UA server is no longer responsive to any client. This is without effect to the real-time functionality of IPCs.

Affected products

• Beckhoff IPC Diagnostics UA Server: through 3.1.0.1
• Beckhoff TF6100: through 3.3.18
• Beckhoff TwinCAT OPC UA Server: through 2.3.0.12

References

• https://cert.vde.com/en-us/advisories/vde-2020-051
• https://download.beckhoff.com/download/Document/product-security/Advisories/advisory-2021-001.pdf
• https://cert.vde.com/en-us/advisories/vde-2020-051
• https://download.beckhoff.com/download/Document/product-security/Advisories/advisory-2021-001.pdf

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