Out-of-bounds Read in Debevv Nanomodbus

CVE-2026-71256

nanoMODBUS through v1.23.0 contains an out-of-bounds stack read leading to a wild-pointer write in nmbs_read_device_identification_basic / recv_read_device_identification_res in nanomodbus.c. A fixed 3-element stack array order[3] = {0,1,2} maps object IDs to buffer indices. The server-supplied object_id field (0-255, read directly from the wire) is used without any bounds check as buf_index = order[object_id].

Vulnerability class: Buffer Overflow

EPSS: 0.003 (23.7th percentile) — read the EPSS interpretation.