ICS Advisories

Risk evaluation

A vulnerability in the CODESYS Control runtime system allows low-privileged remote attackers to access the PKI folder via CODESYS protocol, enabling them to read and write certificates and keys. This exposes sensitive cryptographic data and allows unauthorized certificates to be trusted. However, all services remain available, only certificate based encryption and signing features are concerned. The issue affects systems using the optional CmpOpenSSL component for cryptographic operations. **Update 1.1.0, 01.09.2025:** Updated remediation category - fixed SL runtimes are now available.

Mitigation summary

Update the following products to version 3.5.21.20. * CODESYS Control RTE (SL) * CODESYS Control RTE (for Beckhoff CX) SL * CODESYS Control Win (SL) * CODESYS HMI (SL) * CODESYS Runtime Toolkit The CODESYS Development System and the products available as CODESYS add-ons can be downloaded and installed directly with the CODESYS Installer or be downloaded from the CODESYS Store. Alternatively, as well as for all other products, you will find further information on obtaining the software update in the CODESYS Update area https://www.codesys.com/download/. Following our general recommendation that the PKI should only be managed via the dedicated X.509 API or the corresponding online services of the CODESYS Control runtime system, the programmatic direct access via SysFile or SysDir operations or online access via the CODESYS file transfer services is denied after an update to a fixed product version. For compatibility reasons, the old behavior can be restored for applications that use these accesses via the following setting: [CmpOpenSSL] EnforceBlacklistOnPKIDir=0 However, we strongly recommend keeping the new default.