Overview
CVE-2025-41739 describes a medium severity vulnerability affecting the CODESYS Control runtime system, specifically impacting installations on Linux and QNX operating systems. This vulnerability allows an unauthenticated remote attacker to potentially cause a denial-of-service (DoS) condition. The root cause lies in a race condition that can be exploited during socket communication, leading to an out-of-bounds read. Understanding the technical details and implementing the appropriate mitigation steps is crucial for protecting systems running CODESYS.
Technical Details
The vulnerability stems from a race condition within the communication servers of the CODESYS Control runtime system. An unauthenticated attacker can exploit this race condition by sending specifically crafted socket communications. Successful exploitation allows the attacker to trigger an out-of-bounds read operation. The specific memory location read outside of the allocated buffer is not publicly detailed, but the outcome is the destabilization of the affected service or system, ultimately leading to a denial-of-service condition. The vulnerability is triggered by malformed or specially timed network packets targeting the CODESYS runtime.
CVSS Analysis
The vulnerability has been assigned a CVSS score of 5.9 (MEDIUM). This score reflects the following characteristics:
- Attack Vector: Network (AV:N) – The vulnerability is exploitable over a network.
- Attack Complexity: High (AC:H) – Exploiting the race condition requires precise timing and potentially a deep understanding of the CODESYS communication protocol.
- Privileges Required: None (PR:N) – No authentication is required to exploit the vulnerability.
- User Interaction: None (UI:N) – No user interaction is required to exploit the vulnerability.
- Scope: Unchanged (S:U) – An exploited vulnerability can only affect resources managed by the same security authority.
- Confidentiality Impact: None (C:N) – No confidentiality impact because the attacker is only able to cause a denial of service.
- Integrity Impact: None (I:N) – No integrity impact because the attacker is only able to cause a denial of service.
- Availability Impact: High (A:H) – The attacker can cause a denial of service, impacting the availability of the affected system.
Possible Impact
A successful exploitation of CVE-2025-41739 can result in a denial-of-service condition, potentially disrupting critical industrial processes controlled by the CODESYS runtime system. This can lead to:
- Loss of control over industrial equipment.
- Production downtime.
- Potential safety hazards in industrial environments.
- Unavailability of critical services.
Mitigation and Patch Steps
The recommended mitigation is to apply the official patch provided by CODESYS as soon as it becomes available. Contact CODESYS directly or monitor their security advisories page for patch releases and detailed instructions. In the interim, consider the following mitigating controls:
- Network Segmentation: Isolate the CODESYS runtime environment from untrusted networks using firewalls and VLANs.
- Access Control Lists (ACLs): Implement strict ACLs to limit network access to the CODESYS runtime system only to authorized devices and personnel.
- Intrusion Detection/Prevention Systems (IDS/IPS): Deploy IDS/IPS solutions capable of detecting and blocking malicious network traffic targeting the CODESYS runtime. Configure them with signatures specific to CODESYS protocols and known attack patterns.
- Regular Monitoring: Continuously monitor the CODESYS runtime environment for suspicious activity and anomalies.
- Vendor Communication: Maintain open communication with CODESYS to stay informed about security updates and best practices.
