CVE-2021-21867: Codesys

High severity, CVSS 7.8. EPSS: 1.6% chance of exploitation in the next 30 days.

An unsafe deserialization vulnerability exists in the ObjectManager.plugin ObjectStream.ProfileByteArray functionality of CODESYS GmbH CODESYS Development System 3.5.16 and 3.5.17. A specially crafted file can lead to arbitrary command execution. An attacker can provide a malicious file to trigger this vulnerability.

Affected products

• Codesys Codesys: version 3.5.16.0 only; version 3.5.17.0 only

Published 2021-08-18. Last modified 2026-06-17.