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Vulnerability record · CVE-2026-71254 · published 5 August 2026

CVE-2026-71254: Out-of-bounds write vulnerability

nanoMODBUS through v1.23.0 contains an out-of-bounds write in the Modbus server-side handle_read_file_record function (FC 0x14, Read File Record) in nanomodbus.c. The function validates that the total request size does not exceed 245 bytes and that each sub-request's record_length is at most 124, but it never validates the CUMULATIVE response size across all sub-requests before processing them.

9.8 CVSS 3.1 Critical EPSS 0.55% · top 56.0% CWE-787 · Out-of-bounds write Deferred
9.8CVSS 3.1 base score
0.55%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
2References
26 Aug 2026Last modified by NVD

Description

nanoMODBUS through v1.23.0 contains an out-of-bounds write in the Modbus server-side handle_read_file_record function (FC 0x14, Read File Record) in nanomodbus.c. The function validates that the total request size does not exceed 245 bytes and that each sub-request's record_length is at most 124, but it never validates the CUMULATIVE response size across all sub-requests before processing them.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References

LinkTags
https://github.com/debevv/nanoMODBUS
https://github.com/debevv/nanoMODBUS/blob/master/nanomodbus.c

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Source: NIST National Vulnerability Database (record CVE-2026-71254), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.