CVE-2026-71254

CRITICALCVSS 9.8/10EPSS 0.48%

Last modified

CVE-2026-71254 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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.. EPSS estimates a 0.48% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
9.8/10

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

EPSS Probability
0.48%

38.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
debevvnanoMODBUS<= 1.23.0

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-71254?
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.
How severe is CVE-2026-71254?
CVE-2026-71254 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.48% probability of exploitation in the next 30 days.
How do I fix CVE-2026-71254?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST