RustFS's Missing Post Policy Validation leads to Arbitrary Object Write

{
  "id": "07dd447797d2bcc45954e07d9124f1f6860db192b378b4c8fee1df02cc072be8",
  "url": "https://osv.dev/vulnerability/CVE-2026-27607",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "RustFS's Missing Post Policy Validation leads to Arbitrary Object Write",
    "summary": "RustFS is a distributed object storage system built in Rust. In versions 1.0.0-alpha.56 through 1.0.0-alpha.82, RustFS does not validate policy conditions in presigned POST uploads (PostObject), allowing attackers to bypass content-length-range, starts-with, and Content-Type constraints. This enables unauthorized file uploads exceeding size limits, uploads to arbitrary object keys, and content-type spoofing, potentially leading to storage exhaustion, unauthorized data access, and security bypasses. Version 1.0.0-alpha.83 fixes the issue.",
    "evidence": "osv:CVE-2026-27607",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-27607",
      "aliases": [
        "CVE-2026-27607",
        "GHSA-w5fh-f8xh-5x3p"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/rustfs/rustfs",
              "type": "GIT",
              "events": [
                {
                  "introduced": "3f717292bf69a6cf5fffa0e41253fd1ce08ec5cb"
                },
                {
                  "fixed": "9824171995b58da071c18b5243299bc69e6ec4a7"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "1.0.0-alpha.56"
                      },
                      {
                        "fixed": "1.0.0-alpha.83"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "1.0.0-alpha.56"
                      },
                      {
                        "last_affected": "1.0.0-alpha.82"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "1.0.0-alpha.82",
            "1.0.0-alpha.81",
            "1.0.0-alpha.80",
            "1.0.0-alpha.79",
            "1.0.0-alpha.78",
            "1.0.0-alpha.77",
            "1.0.0-alpha.76",
            "1.0.0-alpha.75",
            "1.0.0-alpha.74",
            "1.0.0-alpha.73",
            "1.0.0-alpha.72",
            "1.0.0-alpha.71",
            "1.0.0-alpha.70",
            "1.0.0-alpha.69",
            "1.0.0-alpha.68",
            "1.0.0-alpha.67",
            "1.0.0-alpha.66",
            "1.0.0-alpha.65",
            "1.0.0-alpha.64",
            "1.0.0-alpha.63",
            "1.0.0-alpha.62",
            "1.0.0-alpha.61",
            "1.0.0-alpha.60",
            "1.0.0-alpha.59",
            "1.0.0-alpha.58",
            "1.0.0-alpha.57",
            "1.0.0-alpha.56"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-27607.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:27.751283130Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27607.json",
        "https://github.com/rustfs/rustfs/security/advisories/GHSA-w5fh-f8xh-5x3p",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-27607"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-20",
          "CWE-863"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27607.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-27607",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 494295,
  "published_at": "2026-02-25T02:10:28.086+00:00"
}