A heap-based buffer overflow exists in lib60870-C 2.4.0 in the server-side FileSegment ASDU encoding path. The issue occurs because FileSegment_encode() validat…

A heap-based buffer overflow vulnerability exists in lib60870-C version 2.4.0, specifically in the server-side FileSegment ASDU encoding path. The vulnerability is triggered because FileSegment_encode() only validates the standalone segment length using FileSegment_GetMaxDataSize() but fails to verify the residual capacity of the current ASDU frame prior to encoding object fields and segment data. This flaw can result in heap memory corruption during IEC 60870-5 protocol communication. lib60870-C is an open-source implementation of the IEC 60870-5-101/104 protocol commonly used in industrial control and critical infrastructure environments. An attacker exploiting this vulnerability could potentially cause a denial of service or achieve remote code execution on affected systems. The issue is tracked under CVE-2026-67873 and was disclosed via the NVD and the project's GitHub repository.