RustFS: OPA policy plugin omits ExistingObjectTag conditions, allowing tag-based authorization policies to treat tagged objects as untagged

{
  "id": "f99548400aba1b5abf769c12973b02e9433048527451b03b22c0bdc92c5ce185",
  "url": "https://osv.dev/vulnerability/CVE-2026-73285",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "RustFS: OPA policy plugin omits ExistingObjectTag conditions, allowing tag-based authorization policies to treat tagged objects as untagged",
    "summary": "RustFS is a distributed object storage system built in Rust. From 1.0.0-alpha.64 until 1.0.0-rc.1, RustFS external OPA authorization enabled by RUSTFS_POLICY_PLUGIN_URL in crates/iam/src/sys.rs sets PreparedIamAuth.needs_existing_object_tag incorrectly for PreparedIamMode::Opa, causing maybe_merge_object_tag_conditions to omit s3:ExistingObjectTag/* values and allowing authenticated users to bypass tag-based policy restrictions. This issue is fixed in version 1.0.0-rc.1.",
    "evidence": "osv:CVE-2026-73285",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-73285",
      "aliases": [
        "CVE-2026-73285",
        "GHSA-5w8r-p896-6vq2"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/rustfs/rustfs",
              "type": "GIT",
              "events": [
                {
                  "introduced": "7f24dbda198f4a9c6d73728dcb07710fb1b14c12"
                },
                {
                  "fixed": "778f1dfa2155cbbc61ad54e6896de9e29d2c4d8d"
                },
                {
                  "fixed": "98d3619613722308498494d412797a52ea8ae64d"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "1.0.0-alpha.64"
                      },
                      {
                        "fixed": "1.0.0-rc.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "98d3619613722308498494d412797a52ea8ae64d"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "778f1dfa2155cbbc61ad54e6896de9e29d2c4d8d"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "1.0.0-rc.1"
                  }
                ]
              }
            }
          ],
          "versions": [
            "1.0.0-beta.12-preview.1",
            "1.0.0-beta.12",
            "1.0.0-beta.11-preview.1",
            "1.0.0-beta.11",
            "1.0.0-beta.10-preview.5",
            "1.0.0-beta.10",
            "1.0.0-beta.10-preview.4",
            "1.0.0-beta.10-preview.3",
            "1.0.0-beta.10-preview.2",
            "1.0.0-beta.10-preview.1",
            "1.0.0-beta.9",
            "1.0.0-beta.8",
            "1.0.0-beta.7",
            "1.0.0-beta.6",
            "1.0.0-beta.5",
            "1.0.0-beta.4",
            "1.0.0-beta.3",
            "1.0.0-beta.2",
            "v1.0.0-beta.1",
            "1.0.0-beta.1",
            "1.0.0-alpha.99",
            "1.0.0-alpha.98",
            "1.0.0-alpha.97",
            "1.0.0-alpha.96",
            "1.0.0-alpha.95",
            "1.0.0-alpha.94",
            "1.0.0-alpha.93",
            "1.0.0-alpha.92",
            "1.0.0-alpha.91",
            "1.0.0-alpha.90",
            "1.0.0-alpha.89",
            "1.0.0-alpha.88",
            "1.0.0-alpha.87",
            "1.0.0-alpha.86",
            "1.0.0-alpha.85",
            "1.0.0-alpha.84",
            "1.0.0-alpha.83",
            "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"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-73285.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:31.693537660Z",
      "provider": "osv",
      "references": [
        "https://github.com/rustfs/rustfs/releases/tag/1.0.0-rc.1",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73285.json",
        "https://github.com/rustfs/rustfs/blob/380ed40b471887014fe21d069b61df9eacca074b/.agents/skills/security-advisory-lessons/references/advisory-patterns.md?plain=1#L47",
        "https://github.com/rustfs/rustfs/security/advisories/GHSA-5w8r-p896-6vq2",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-73285",
        "https://github.com/rustfs/rustfs/commit/98d3619613722308498494d412797a52ea8ae64d"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-863"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73285.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-73285",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 498606,
  "published_at": "2026-08-12T14:37:42.271+00:00"
}