What’s Vulnerable › Vulnerabilities

CVE-2019-5636: Beckhoff TwinCAT Discovery Service Denial of Service

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2019-11-21 · updated 2026-06-17
• Weakness: CWE-404

Description

When a Beckhoff TwinCAT Runtime receives a malformed UDP packet, the ADS Discovery Service shuts down. Note that the TwinCAT devices are still performing as normal. This issue affects TwinCAT 2 version 2304 (and prior) and TwinCAT 3.1 version 4204.0 (and prior).

Affected products

• ICS-CERT Beckhoff TwinCAT: 2.0-build2304, 3.1-build4024.0

References

• https://blog.rapid7.com/2019/10/08/r7-2019-32-denial-of-service-vulnerabilities-in-beckhoff-twincat-plc-environment-fixed/
• https://download.beckhoff.com/download/Document/product-security/Advisories/advisory-2019-004.pdf
• https://blog.rapid7.com/2019/10/08/r7-2019-32-denial-of-service-vulnerabilities-in-beckhoff-twincat-plc-environment-fixed/
• https://download.beckhoff.com/download/Document/product-security/Advisories/advisory-2019-004.pdf

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