CVE-2026-54410

Description

nanoMODBUS through v1.23.0 contains an off-by-one buffer overflow in the recv_msg_header() function of the Modbus/TCP server that allows remote unauthenticated attackers to write one attacker-controlled byte past the end of the 260-byte receive buffer by sending a crafted MBAP frame whose Length field is set to 255. The overflow corrupts the adjacent buffer-index field of the nanoMODBUS state structure, resulting in denial of service through invalid memory accesses and, on bare-metal and RTOS targets without memory protection, one-byte information disclosure and writes to unintended register addresses on the Write Multiple Registers (FC16) handler path.

CVSS v3.1 Score

8.6

HIGH

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

EPSS — Exploit Prediction

0.0054

Probability of exploitation

0.41%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-193 CWE-193

CWE-787 Out-of-bounds Write

References

Other References

https://cwe.mitre.org/data/definitions/193.html https://cwe.mitre.org/data/definitions/787.html https://github.com/debevv/nanoMODBUS https://github.com/debevv/nanoMODBUS/blob/v1.23.0/nanomodbus.c#L369

Frequently Asked Questions

What is CVE-2026-54410? +

nanoMODBUS through v1.23.0 contains an off-by-one buffer overflow in the recv_msg_header() function of the Modbus/TCP server that allows remote unauthenticated attackers to write one attacker-controlled byte past the end of the 260-byte receive buffer by sending a crafted MBAP frame whose Length field is set to 255. The overflow corrupts the adjacent buffer-index field of the nanoMODBUS state structure, resulting in denial of service through invalid memory accesses and, on bare-metal and RTOS targets without memory protection, one-byte information disclosure and writes to unintended register addresses on the Write Multiple Registers (FC16) handler path. It has a CVSS v3.1 base score of 8.6 (HIGH).

How severe is CVE-2026-54410? +

CVE-2026-54410 has a CVSS v3.1 score of 8.6 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0054, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-54410? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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