rustsec-2025-0020
Vulnerability from osv_rustsec
Published
2025-04-01 12:00
Modified
2025-10-28 06:02
Summary
Risk of buffer overflow in `PyString::from_object`
Details

PyString::from_object took &str arguments and forwarded them directly to the Python C API without checking for terminating nul bytes. This could lead the Python interpreter to read beyond the end of the &str data and potentially leak contents of the out-of-bounds read (by raising a Python exception containing a copy of the data including the overflow).

In PyO3 0.24.1 this function will now allocate a CString to guarantee a terminating nul bytes. PyO3 0.25 will likely offer an alternative API which takes &CStr arguments.

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{
  "affected": [
    {
      "database_specific": {
        "categories": [
          "memory-exposure"
        ],
        "cvss": null,
        "informational": null
      },
      "ecosystem_specific": {
        "affected_functions": null,
        "affects": {
          "arch": [],
          "functions": [
            "pyo3::types::PyString::from_object",
            "pyo3::types::PyString::from_object_bound"
          ],
          "os": []
        }
      },
      "package": {
        "ecosystem": "crates.io",
        "name": "pyo3",
        "purl": "pkg:cargo/pyo3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.0.0-0"
            },
            {
              "fixed": "0.24.1"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": []
    }
  ],
  "aliases": [
    "GHSA-pph8-gcv7-4qj5"
  ],
  "database_specific": {
    "license": "CC0-1.0"
  },
  "details": "`PyString::from_object` took `\u0026str` arguments and forwarded them directly to the Python C API without checking for terminating nul bytes. This could lead the Python interpreter to read beyond the end of the `\u0026str` data and potentially leak contents of the out-of-bounds read (by raising a Python exception containing a copy of the data including the overflow).\n\nIn PyO3 0.24.1 this function will now allocate a `CString` to guarantee a terminating nul bytes. PyO3 0.25 will likely offer an alternative API which takes `\u0026CStr` arguments.",
  "id": "RUSTSEC-2025-0020",
  "modified": "2025-10-28T06:02:18Z",
  "published": "2025-04-01T12:00:00Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://crates.io/crates/pyo3"
    },
    {
      "type": "ADVISORY",
      "url": "https://rustsec.org/advisories/RUSTSEC-2025-0020.html"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/PyO3/pyo3/issues/5005"
    }
  ],
  "related": [],
  "severity": [],
  "summary": "Risk of buffer overflow in `PyString::from_object`"
}


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