CVE-2025-63927 identifies a heap-use-after-free vulnerability in the airpig2011 IEC104 protocol implementation, specifically introduced through commit be6d841 dated 2019-07-08. The vulnerability occurs in the multi-threaded client function Iec10x_Scheduled, where the program accesses memory that has already been freed. This use-after-free condition can cause undefined behavior, including program crashes or memory corruption. The flaw arises from improper memory management in a concurrent execution context, which is critical in industrial communication protocols like IEC104 that are widely used for supervisory control and data acquisition (SCADA) systems. Exploiting this vulnerability could allow an attacker to trigger denial-of-service (DoS) conditions by crashing the client application or corrupting memory to potentially alter program execution. Although no known exploits are currently reported in the wild, the vulnerability poses a risk to systems relying on this implementation. The absence of a CVSS score indicates the need for an independent severity assessment. The vulnerability does not require authentication or user interaction, increasing its risk profile. The lack of detailed affected versions and patch information suggests that users should audit their implementations for the vulnerable commit and apply appropriate code reviews or patches. Given the critical role of IEC104 in industrial environments, this vulnerability could impact operational continuity and safety.

For European organizations, particularly those operating critical infrastructure such as energy grids, water treatment, and manufacturing facilities that use IEC104 protocol implementations, this vulnerability could lead to significant operational disruptions. A successful exploitation could cause denial-of-service by crashing control system clients, potentially halting monitoring and control operations. Memory corruption could also lead to unpredictable behavior, possibly affecting data integrity and system reliability. This risk is heightened in environments where IEC104 is deployed in multi-threaded client applications managing real-time industrial processes. The impact extends to safety and compliance, as disruptions in industrial control systems can have cascading effects on public safety and regulatory adherence. Additionally, the lack of authentication requirements for exploitation means attackers with network access could trigger these issues remotely, increasing the threat surface. European organizations with legacy or unpatched IEC104 implementations are particularly vulnerable, and the absence of known exploits should not lead to complacency given the potential severity.

Organizations should first identify all instances of the airpig2011 IEC104 implementation in their environments, especially those using multi-threaded clients. Since no official patches or version details are provided, a code audit focusing on the Iec10x_Scheduled function and related memory management routines is critical. Developers should implement safe memory handling practices, such as ensuring pointers are not used after free and employing synchronization mechanisms to prevent concurrent access issues. Where possible, upgrading to newer, secure versions of the IEC104 implementation or switching to alternative, well-maintained protocol stacks is advisable. Network segmentation and strict access controls should be enforced to limit exposure of IEC104 clients to untrusted networks. Monitoring for unusual crashes or memory errors in IEC104 clients can provide early detection of exploitation attempts. Finally, organizations should engage with vendors or open-source maintainers to obtain patches or mitigations and apply them promptly once available.