CVE-2026-71254: Debevv Nanomodbus

Critical severity, CVSS 9.8. EPSS: 0.6% chance of exploitation in the next 30 days.

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.

Affected products

• Debevv Nanomodbus: up to and including 1.23.0

Published 2026-08-05. Last modified 2026-08-26.