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'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.

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History

Fri, 08 May 2026 17:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-121
Metrics cvssV3_1

{'score': 8.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 08 May 2026 16:00:00 +0000

Type Values Removed Values Added
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'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.
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cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published:

Updated: 2026-05-08T15:59:03.619Z

Reserved: 2026-03-04T00:00:00.000Z

Link: CVE-2026-29972

cve-icon Vulnrichment

Updated: 2026-05-08T15:58:57.641Z

cve-icon NVD

Status : Received

Published: 2026-05-08T16:16:09.960

Modified: 2026-05-08T17:16:30.100

Link: CVE-2026-29972

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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