General Recommendation

As part of a security strategy, CODESYS GmbH strongly recommends at least the following best-practice defense measures:

• Use controllers and devices only in a protected environment to minimize network exposure and ensure that they are not accessible from outside
• Use firewalls to protect and separate the control system network from other networks
• Activate and apply user management and password features
• Limit the access to both development and control system by physical means, operating system features, etc.
• Use encrypted communication links
• Use VPN (Virtual Private Networks) tunnels if remote access is required
• Protect both development and control system by using up to date virus detecting solutions

For more information and general recommendations for protecting machines and plants, see also the CODESYS Security Whitepaper here.

Mitigation

The vulnerability can be mitigated by restricting the allowed login authentication type "CmpUserMgr/UserLogin_AuthenticationType" to "ONLY_ASYMMETRIC". This can be configured either via the Device Security Settings dialog in the CODESYS Development System or directly in the configuration file of the CODESYS Control runtime system (CODESYSControl.cfg) by adding the following setting:

[CmpUserMgr] SECURITY.UserLogin_AuthenticationType=ONLY_ASYMMETRIC

With this configuration in place, both potential attackers and legacy CODESYS protocol clients (prior to version 3.5.16.0) will be blocked from logging in, thereby preventing execution of the vulnerable code path.

Remediation

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 Runtime Toolkit

Update the following products to version 4.17.0.0. The release of this version is expected for August 2025.

• CODESYS Control for BeagleBone SL
• CODESYS Control for emPC-A/iMX6 SL
• CODESYS Control for IOT2000 SL
• CODESYS Control for Linux ARM SL
• CODESYS Control for Linux SL
• CODESYS Control for PFC100 SL
• CODESYS Control for PFC200 SL
• CODESYS Control for PLCnext SL
• CODESYS Control for Raspberry Pi SL
• CODESYS Control for WAGO Touch Panels 600 SL
• CODESYS Virtual Control SL

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/.