CVE-2025-63927 identifies a heap-use-after-free vulnerability in the airpig2011 IEC104 protocol implementation, introduced through commit be6d841 dated July 8, 2019. The vulnerability manifests in the multi-threaded client execution environment within the function Iec10x_Scheduled, which improperly accesses memory that has already been freed. This use-after-free condition can cause undefined behavior including program crashes or memory corruption. The flaw stems from improper memory management in a concurrent context, which is a common source of instability and security issues in software handling real-time or industrial communication protocols. While the vulnerability does not directly compromise confidentiality or integrity, it can be exploited to cause denial-of-service (DoS) conditions by crashing the affected application or corrupting its memory space. The CVSS v3.1 score is 4.0 (medium), reflecting local attack vector (AV:L), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), and impact limited to availability (A:L). No patches or known exploits are currently available, indicating that the vulnerability is newly disclosed and may require vendor action to remediate. The CWE classification is CWE-122, which corresponds to heap-based buffer errors, specifically use-after-free conditions. This vulnerability is relevant for systems using the airpig2011 IEC104 implementation, commonly found in industrial control systems and SCADA environments that communicate using the IEC 60870-5-104 protocol for telecontrol.

For European organizations, especially those operating critical infrastructure such as energy grids, manufacturing plants, and transportation systems that rely on IEC104 protocol implementations like airpig2011, this vulnerability poses a risk of operational disruption. Exploitation could lead to denial-of-service conditions, causing system outages or degraded performance in industrial control environments. While it does not directly expose sensitive data or allow unauthorized control, the resulting instability could impact availability of critical services. This is particularly concerning in sectors where continuous operation is essential for safety and economic stability. The local attack vector means that attackers need some form of access to the network or system running the vulnerable software, which may be feasible in environments with insufficient network segmentation or insider threats. The absence of known exploits currently reduces immediate risk, but the medium severity rating and potential for memory corruption warrant proactive mitigation. Disruptions in industrial control systems can have cascading effects on supply chains and public services across Europe.

1. Restrict access to systems running the airpig2011 IEC104 implementation by enforcing strict network segmentation and access controls to limit local access. 2. Monitor logs and system behavior for signs of crashes or abnormal memory errors related to the Iec10x_Scheduled function, enabling early detection of exploitation attempts. 3. Implement runtime protections such as memory safety tools or address sanitizers in test environments to identify and mitigate use-after-free conditions. 4. Engage with the vendor or maintainers of airpig2011 IEC104 to obtain patches or updates addressing this vulnerability as soon as they become available. 5. Conduct thorough code reviews and testing of multi-threaded components in industrial communication software to identify similar concurrency-related memory management issues. 6. Prepare incident response plans specifically for industrial control system disruptions, including fallback procedures to maintain operational continuity. 7. Educate operational technology (OT) personnel about the risks of local access vulnerabilities and enforce strict physical and logical access policies.