{
  "document": {
    "category": "csaf_vex",
    "csaf_version": "2.0",
    "lang": "en-US",
    "publisher": {
      "category": "coordinator",
      "contact_details": "https://www.cisa.gov/report",
      "issuing_authority": "CISA",
      "name": "CISA",
      "namespace": "https://www.cisa.gov/"
    },
    "title": "ONNX symlink-following and path-traversal arbitrary file write",
    "tracking": {
      "current_release_date": "2026-08-21T15:41:33Z",
      "generator": {
        "engine": {
          "name": "VINCE-NT",
          "version": "1.15.0+build.101"
        }
      },
      "id": "VA-26-233-01",
      "initial_release_date": "2026-08-21T15:41:33Z",
      "status": "final",
      "version": "1.0.0",
      "revision_history": [
        {
          "number": "1.0.0",
          "summary": "Initial publication",
          "date": "2026-08-21T15:41:33Z"
        }
      ]
    },
    "distribution": {
      "tlp": {
        "label": "WHITE"
      }
    },
    "notes": [
      {
        "text": "All information products included in [https://github.com/cisagov/CSAF/tree/develop/csaf_files/IT/white](https://github.com/cisagov/CSAF/tree/develop/csaf_files/IT/white) are provided \\\"as is\\\" for informational purposes only. The Department of Homeland Security (DHS) does not provide any warranties of any kind regarding any information contained within. DHS does not endorse any commercial product or service, referenced in this product or otherwise. Further dissemination of this product is governed by the Traffic Light Protocol (TLP) marking in the header. For more information about TLP, see [https://us-cert.cisa.gov/tlp/](https://us-cert.cisa.gov/tlp/).",
        "title": "Legal Notice",
        "category": "legal_disclaimer"
      },
      {
        "text": "Worldwide",
        "title": "Countries and Areas Deployed",
        "category": "other"
      },
      {
        "text": "Information Technology",
        "title": "Critical Infrastructure Sectors",
        "category": "other"
      },
      {
        "text": "A local attacker with write access to the directory where a victim serializes external data can deterministically pre-plant a symlink that is being followed, causing the victim's write to append to any file the victim can write, e.g. ~/.ssh/authorized_keys, cron files, or application configs.",
        "title": "Risk Evaluation",
        "category": "summary"
      },
      {
        "text": "Fixed in 1.21.0.",
        "title": "Recommended Practices",
        "category": "general"
      },
      {
        "text": "United States",
        "title": "Company Headquarters Location",
        "category": "other"
      }
    ],
    "references": [
      {
        "url": "https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-233-01.json",
        "summary": "Vulnerability Advisory VA-26-233-01 CSAF",
        "category": "self"
      }
    ]
  },
  "product_tree": {
    "branches": [
      {
        "category": "vendor",
        "name": "ONNX",
        "branches": [
          {
            "category": "product_name",
            "name": "ONNX",
            "branches": [
              {
                "category": "product_version_range",
                "name": "<1.21.0",
                "product": {
                  "name": "ONNX ONNX <1.21.0",
                  "product_id": "CSAFPID-0001"
                }
              },
              {
                "category": "product_version",
                "name": "1.21.0",
                "product": {
                  "name": "ONNX ONNX 1.21.0",
                  "product_id": "CSAFPID-0002"
                }
              }
            ]
          }
        ]
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-49114",
      "cwe": {
        "id": "CWE-367",
        "name": "Time-of-check Time-of-use (TOCTOU) Race Condition"
      },
      "notes": [
        {
          "category": "summary",
          "text": "In ONNX before 1.21.0, the 'save_external_data' function builds the external-data file path from the model's external_data location field and opens it for writing without 'O_NOFOLLOW/O_EXCL', after a non-atomic 'os.path.isfile()' check. A local attacker with write access to the directory where a victim serializes external data can deterministically pre-plant a symlink that is being followed, causing the victim's write to append to any file the victim can write, e.g. ~/.ssh/authorized_keys, cron files, or application configs. Fixed in 1.21.0.",
          "title": "Description"
        },
        {
          "category": "details",
          "title": "SSVC",
          "text": "SSVCv2/E:P/A:N/T:P/2026-05-27T16:00:11Z/"
        }
      ],
      "title": "ONNX symlink-following and path-traversal arbitrary file write",
      "product_status": {
        "known_affected": [
          "CSAFPID-0001"
        ],
        "fixed": [
          "CSAFPID-0002"
        ]
      },
      "references": [
        {
          "category": "external",
          "summary": "github.com",
          "url": "https://github.com/onnx/onnx/security/advisories/GHSA-q56x-g2fj-4rj6"
        },
        {
          "category": "external",
          "summary": "VA-26-233-01 CSAF",
          "url": "https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-233-01.json"
        },
        {
          "category": "external",
          "summary": "CVE-2026-49114",
          "url": "https://www.cve.org/CVERecord?id=CVE-2026-49114"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H",
            "version": "3.1"
          },
          "products": [
            "CSAFPID-0001"
          ]
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "details": "Fixed in 1.21.0.",
          "url": "https://github.com/onnx/onnx/security/advisories/GHSA-q56x-g2fj-4rj6",
          "product_ids": [
            "CSAFPID-0001"
          ],
          "date": "2026-03-31T00:00:00Z"
        },
        {
          "category": "vendor_fix",
          "details": "Fixed in 1.21.0.",
          "url": "https://github.com/onnx/onnx/security/advisories/GHSA-q56x-g2fj-4rj6",
          "product_ids": [
            "CSAFPID-0002"
          ],
          "date": "2026-03-31T00:00:00Z"
        }
      ],
      "acknowledgments": [
        {
          "names": [
            "tsigouris007"
          ]
        },
        {
          "names": [
            "kpatsakis"
          ]
        }
      ],
      "release_date": "2026-03-31T00:00:00Z"
    }
  ]
}