ONNX: Denial of service via unchecked expansion of packed sub-byte tensors in ONNX Python APIs

{
  "id": "75c9e77a16bb59af44dfe1cedfc5cd5b862f75fce11a4ffcdbccad79c1a59561",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-115922",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ONNX: Denial of service via unchecked expansion of packed sub-byte tensors in ONNX Python APIs",
    "summary": "Open Neural Network Exchange (ONNX) is an open standard for machine learning interoperability. Prior to 1.22.0, _unpack_2bit() and _unpack_4bit() resize unpacked arrays according to attacker-controlled TensorProto.dims without verifying that raw_data or int32_data encodes the declared number of elements. Materializing an untrusted UINT2, INT2, UINT4, INT4, or FLOAT4E2M1 tensor through onnx.numpy_helper.to_array() or onnx.reference.ReferenceEvaluator can therefore expand a small packed payload into a disproportionately large allocation and exhaust memory. This issue is fixed in version 1.22.0.",
    "evidence": "cve:CVE-2026-115922",
    "products": [
      {
        "name": {
          "value": "onnx",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-115922",
      "aliases": [
        "CVE-2026-115922"
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "scope": "UNCHANGED",
            "version": "3.1",
            "baseScore": 6.2,
            "attackVector": "LOCAL",
            "baseSeverity": "MEDIUM",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "integrityImpact": "NONE",
            "userInteraction": "NONE",
            "attackComplexity": "LOW",
            "availabilityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "confidentialityImpact": "NONE"
          }
        }
      ],
      "affected": [
        {
          "vendor": "onnx",
          "product": "onnx",
          "versions": [
            {
              "status": "affected",
              "version": "< 1.22.0"
            }
          ]
        }
      ],
      "modified": "2026-10-26T17:31:03.716Z",
      "provider": "cve",
      "references": [
        "https://github.com/onnx/onnx/security/advisories/GHSA-q69g-f4f5-v8m7",
        "https://github.com/onnx/onnx/pull/8033",
        "https://github.com/onnx/onnx/pull/8038",
        "https://github.com/onnx/onnx/pull/8066",
        "https://github.com/onnx/onnx/commit/05c1bc3bceceb8d3cf11e9e7fc7f19f971c44988",
        "https://github.com/onnx/onnx/commit/8de2cf6aa47928e6515ac6d9e1a8b4758886a7df",
        "https://github.com/onnx/onnx/commit/dce5876d6cc6cc30157af7d26a752ef44976da8e",
        "https://github.com/onnx/onnx/releases/tag/v1.22.0"
      ],
      "provider_metadata": {
        "cna": {
          "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
          "shortName": "GitHub_M",
          "dateUpdated": "2026-10-26T17:31:03.716Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-115922",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/containers/cna/metrics"
  },
  "source_id": "core-cve",
  "document_id": 324479,
  "published_at": "2026-10-26T17:31:03.716+00:00"
}