CVE-2022-39823 is a high-severity vulnerability affecting the Softing OPC UA C++ SDK versions 5.66 through 6.x prior to 6.10. The vulnerability arises from improper handling of OPC UA browse requests that exceed the server's limit on continuation points. Specifically, when a client sends a browse request with more continuation points than the server can handle, it triggers a use-after-free (UAF) condition. A use-after-free vulnerability occurs when a program continues to use memory after it has been freed, potentially leading to undefined behavior such as crashes, memory corruption, or arbitrary code execution. In this case, the vulnerability impacts the availability of the OPC UA server component, as the CVSS vector indicates no impact on confidentiality or integrity but a high impact on availability (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). The vulnerability does not require privileges or user interaction to exploit and can be triggered remotely over the network. OPC UA (Open Platform Communications Unified Architecture) is a widely used industrial communication protocol for secure and reliable data exchange in industrial automation and control systems (IACS). The Softing OPC UA C++ SDK is a development toolkit used by vendors and integrators to build OPC UA servers and clients. Exploitation of this vulnerability could allow an unauthenticated attacker to cause denial of service (DoS) conditions by crashing or destabilizing OPC UA servers that use the affected SDK versions. Although no known exploits are reported in the wild, the vulnerability's characteristics make it a credible threat to industrial environments relying on OPC UA for critical operations. The underlying weakness is classified under CWE-416 (Use After Free), a common and dangerous memory corruption issue. The lack of a patch link suggests that users should verify with Softing for updates or mitigations. Given the critical role of OPC UA in industrial automation, this vulnerability demands prompt attention to prevent operational disruptions.

For European organizations, especially those operating in manufacturing, energy, utilities, transportation, and critical infrastructure sectors, this vulnerability poses a significant risk. OPC UA is a foundational protocol in Industry 4.0 deployments and smart factories across Europe. A successful exploitation could lead to denial of service on OPC UA servers, disrupting industrial control systems and potentially halting production lines or critical services. This could result in financial losses, safety hazards, and reputational damage. Since the vulnerability does not affect confidentiality or integrity directly, the primary concern is operational availability. However, prolonged outages or cascading failures in industrial environments could indirectly impact safety and data integrity. European organizations with legacy or unpatched Softing OPC UA SDK implementations are particularly vulnerable. The lack of required authentication and user interaction lowers the barrier for attackers, increasing the likelihood of exploitation attempts. Given Europe's strong regulatory environment around critical infrastructure protection (e.g., NIS Directive), organizations must prioritize addressing this vulnerability to maintain compliance and operational resilience.

1. Immediate verification of the Softing OPC UA C++ SDK version in use is essential. Organizations should identify all OPC UA servers and clients built using versions 5.66 through 6.x prior to 6.10. 2. Apply official patches or updates from Softing as soon as they become available. If no patch is currently released, contact Softing support for guidance or workarounds. 3. Implement network-level protections such as OPC UA protocol filtering and rate limiting to detect and block anomalous browse requests that exceed continuation point limits. 4. Employ intrusion detection/prevention systems (IDS/IPS) with signatures or behavioral rules targeting malformed or excessive OPC UA browse requests to prevent exploitation attempts. 5. Segment industrial networks to isolate OPC UA servers from untrusted or less secure network zones, reducing exposure to remote attackers. 6. Monitor OPC UA server logs and network traffic for unusual browse request patterns or repeated crashes indicative of exploitation attempts. 7. Conduct regular security assessments and penetration testing focused on OPC UA implementations to identify and remediate vulnerabilities proactively. 8. Incorporate secure coding practices and memory management audits in development processes for OPC UA-based applications to prevent similar use-after-free issues.