CVE-2026-71256
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk23th percentile - higher than 23% of all known CVEs
Summary
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].
Risk Assessment
An attacker can cause a process crash or potentially execute arbitrary code by exploiting the out-of-bounds stack read and wild-pointer write.
Recommendation
Add bounds checking for object_id before using it as an array index. Also, update to the latest version of the library if a patch is available.
Original NVD description (English source)
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].