CVE-2026-71255 - nanoMODBUS Client-Side Out-of-Bounds Write via object_length in recv_read_device_identification_res()

CVE-2026-71255 - nanoMODBUS Client-Side Out-of-Bounds Write via object_length in recv_read_device_identification_res()

https://cvefeed.io/rssfeed/latest.atom / Wed, 08/05/2026 - 16:09
CVE ID :CVE-2026-71255
Published : Aug. 5, 2026, 12:18 p.m. | 36 minutes ago
Description :nanoMODBUS through v1.23.0 contains an out-of-bounds write in the Modbus client-side recv_read_device_identification_res() function (FC 0x2B/MEI 0x0E, Read Device Identification) in nanomodbus.c. The server-supplied object_length field (0-246) is validated only against the remaining PDU size (res_size_left) and is never validated against the caller-supplied buffers_length parameter. After copying data with strncpy(buffers_out[buf_index], str, buffers_length), the code unconditionally writes a NUL terminator at buffers_out[buf_index][object_length]. When a malicious or compromised Modbus server sends a response with object_length greater than or equal to the client's buffers_length, this NUL write lands past the end of the caller-provided buffer, corrupting adjacent stack or heap memory on the client.
Severity: 8.6 | HIGH
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