CVE-2026-67873 [CRITICAL] – A heap-based buffer overflow exists in lib60870-C 2.4.0 in the server-side FileSegment ASD

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() validates only the standalone segment length via FileSegment_GetMaxDataSize() and does not verify the residual capacity of the current ASDU frame before encoding object fields and segment data