Vulnerability-Lookup

CVE-2026-71255 (GCVE-0-2026-71255)

Vulnerability from cvelistv5 – Published: 2026-08-05 11:44 – Updated: 2026-08-05 12:52

Title

nanoMODBUS Client-Side Out-of-Bounds Write via object_length in recv_read_device_identification_res()

Summary

nanoMODBUS through v1.23.0 contains an out-of-bounds write in the Modbus client-side recv_read_device_identification_res() function (FC 0x2B/MEI 0x0E, Read Device Identification) in nanomodbus.c. The server-supplied object_length field (0-246) is validated only against the remaining PDU size (res_size_left) and is never validated against the caller-supplied buffers_length parameter. After copying data with strncpy(buffers_out[buf_index], str, buffers_length), the code unconditionally writes a NUL terminator at buffers_out[buf_index][object_length]. When a malicious or compromised Modbus server sends a response with object_length greater than or equal to the client's buffers_length, this NUL write lands past the end of the caller-provided buffer, corrupting adjacent stack or heap memory on the client.

Severity

8.6 (High)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-787

Assigner

TuranSec

References

2 references

URL	Tags
https://github.com/debevv/nanoMODBUS
https://github.com/debevv/nanoMODBUS/blob/master/…

Impacted products

1 product

Vendor	Product	Version
debevv	nanoMODBUS	Affected: 0 , ≤ 1.23.0 (semver)

Credits

Shukhratbek Uraiimov

Show details on NVD website

JSON

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          "url": "https://github.com/debevv/nanoMODBUS/blob/master/nanomodbus.c"
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      ],
      "title": "nanoMODBUS Client-Side Out-of-Bounds Write via object_length in recv_read_device_identification_res()"
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GHSA-9RFP-Q4V5-653H

Vulnerability from github – Published: 2026-08-05 12:31 – Updated: 2026-08-05 12:31

Details

Severity

8.6 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-71255"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-787"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-05T12:18:57Z",
    "severity": "HIGH"
  },
  "details": "nanoMODBUS through v1.23.0 contains an out-of-bounds write in the Modbus client-side recv_read_device_identification_res() function (FC 0x2B/MEI 0x0E, Read Device Identification) in nanomodbus.c. The server-supplied object_length field (0-246) is validated only against the remaining PDU size (res_size_left) and is never validated against the caller-supplied buffers_length parameter. After copying data with strncpy(buffers_out[buf_index], str, buffers_length), the code unconditionally writes a NUL terminator at buffers_out[buf_index][object_length]. When a malicious or compromised Modbus server sends a response with object_length greater than or equal to the client\u0027s buffers_length, this NUL write lands past the end of the caller-provided buffer, corrupting adjacent stack or heap memory on the client.",
  "id": "GHSA-9rfp-q4v5-653h",
  "modified": "2026-08-05T12:31:33Z",
  "published": "2026-08-05T12:31:33Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-71255"
    },
    {
      "type": "WEB",
      "url": "https://github.com/debevv/nanoMODBUS"
    },
    {
      "type": "WEB",
      "url": "https://github.com/debevv/nanoMODBUS/blob/master/nanomodbus.c"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H",
      "type": "CVSS_V3"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

CVE-2026-71255 (GCVE-0-2026-71255)

GHSA-9RFP-Q4V5-653H

Tags

Sightings

Nomenclature