CVE-2026-29972

Severity CVSS v4.0:

Pending analysis

Type:

CWE-121 Stack-based Buffer Overflow

Publication date:

08/05/2026

Last modified:

08/05/2026

Description

nanoMODBUS through v1.22.0 has a stack-based buffer overflow in recv_read_registers_res() in nanomodbus.c. When a client calls nmbs_read_holding_registers() or nmbs_read_input_registers(), the library writes register data from the server response to the caller-provided buffer based on the response&#39;s byte_count field before validating that byte_count matches the requested quantity. A malicious Modbus TCP server can send a response with byte_count=250 (125 registers) regardless of the requested quantity, causing up to 248 bytes of attacker-controlled data to overflow the buffer, potentially allowing remote code execution.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H CVSS v3.1 Severity and Metrics:

Base Score: 8.20 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): Low
Availability (A): High

Base Score 3.x

8.20

Severity 3.x

HIGH

CVE-2026-29972

Description

Impact

References to Advisories, Solutions, and Tools