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CVE-2026-71254— nanoMODBUS Server-Side Out-of-Bounds Write in handle_read_file_record()

Quick assessment

Affected
debevv nanoMODBUS
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Valerio De Benedetto nanoMODBUS是Valerio De Benedetto个人开发者的一款MODBUS通信协议实现库。 Valerio De Benedetto nanoMODBUS 1.23.0及之前版本存在缓冲区错误漏洞，该漏洞源于Modbus服务器端handle_read_file_record()函数（FC 0x14）未验证累积响应大小，导致uint8_t累积器溢出，可能造成越界写入，进而导致拒绝服务或远程代码执行。

CVSS 9.8 · Critical EPSS 0.55% · P44

Possible ATT&CK Techniques 1 AI

T1210 · Exploitation of Remote Services

Affected Version Matrix 1

VendorProduct Version RangeStatus
debevv nanoMODBUS ≤ 1.23.0 affected
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I. Basic Information for CVE-2026-71254

Vulnerability Information
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Vulnerability Title
nanoMODBUS Server-Side Out-of-Bounds Write in handle_read_file_record()
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存写
Source: CVE Program / CVE List V5
Vulnerability Title
Valerio De Benedetto nanoMODBUS 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Valerio De Benedetto nanoMODBUS是Valerio De Benedetto个人开发者的一款MODBUS通信协议实现库。 Valerio De Benedetto nanoMODBUS 1.23.0及之前版本存在缓冲区错误漏洞，该漏洞源于Modbus服务器端handle_read_file_record()函数（FC 0x14）未验证累积响应大小，导致uint8_t累积器溢出，可能造成越界写入，进而导致拒绝服务或远程代码执行。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
debevv nanoMODBUS 0 ~ 1.23.0 -

II. Public POCs for CVE-2026-71254

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 9585 chars
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Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
In-depth vulnerability mechanism
Trigger conditions & impact
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Exploit chain & mitigation
POC zip download
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III. Intelligence Information for CVE-2026-71254

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Other References for CVE-2026-71254 (1)

Same Patch Batch · debevv · 2026-08-05 · 3 CVEs total

CVE-2026-71256 9.8 CRITICAL nanoMODBUS Client-Side Out-of-Bounds Read Leading to Wild-Pointer Write via object_id
CVE-2026-71255 8.6 HIGH nanoMODBUS Client-Side Out-of-Bounds Write via object_length in recv_read_device_identific

IV. Related Vulnerabilities

Same product: nanoMODBUS
Same vendor: debevv
Same weakness: CWE-787

V. Comments for CVE-2026-71254

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