GHSA-5HC8-P74Q-47PP

Vulnerability from github – Published: 2026-05-08 18:31 – Updated: 2026-05-08 18:31
VLAI?
Details

nanoMODBUS through v1.22.0 has a stack-based buffer overflow in recv_read_registers_res() in nanomodbus.c. When a client calls nmbs_read_holding_registers() or nmbs_read_input_registers(), the library writes register data from the server response to the caller-provided buffer based on the response's byte_count field before validating that byte_count matches the requested quantity. A malicious Modbus TCP server can send a response with byte_count=250 (125 registers) regardless of the requested quantity, causing up to 248 bytes of attacker-controlled data to overflow the buffer, potentially allowing remote code execution.

Severity ?
8.2 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-29972"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-121"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-08T16:16:09Z",
    "severity": "HIGH"
  },
  "details": "nanoMODBUS through v1.22.0 has a stack-based buffer overflow in recv_read_registers_res() in nanomodbus.c. When a client calls nmbs_read_holding_registers() or nmbs_read_input_registers(), the library writes register data from the server response to the caller-provided buffer based on the response\u0027s byte_count field before validating that byte_count matches the requested quantity. A malicious Modbus TCP server can send a response with byte_count=250 (125 registers) regardless of the requested quantity, causing up to 248 bytes of attacker-controlled data to overflow the buffer, potentially allowing remote code execution.",
  "id": "GHSA-5hc8-p74q-47pp",
  "modified": "2026-05-08T18:31:34Z",
  "published": "2026-05-08T18:31:34Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-29972"
    },
    {
      "type": "WEB",
      "url": "https://gist.github.com/dwilliams27/a4e26fe747c8561d608f7549804bd85f"
    },
    {
      "type": "WEB",
      "url": "https://github.com/debevv/nanoMODBUS"
    },
    {
      "type": "WEB",
      "url": "https://github.com/debevv/nanoMODBUS/blob/master/nanomodbus.c#L580-L615"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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