MinIO has JWT Algorithm Confusion in OIDC Authentication

{
  "id": "999a70f03abc2cf9fa8acea3d838b5023b65a039d28f11f0326455e282fd1433",
  "url": "https://osv.dev/vulnerability/GHSA-5cx5-wh4m-82fh",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "MinIO has JWT Algorithm Confusion in OIDC Authentication",
    "summary": "### Impact _What kind of vulnerability is it? Who is impacted?_ A JWT algorithm confusion vulnerability in MinIO's OpenID Connect authentication allows an attacker who knows the OIDC `ClientSecret` to forge arbitrary identity tokens and obtain S3 credentials with any policy, including `consoleAdmin`. An attacker with knowledge of the OIDC `ClientSecret` can: - Impersonate any user identity - Obtain S3 credentials with any IAM policy, including `consoleAdmin` - Access, modify, or delete any data in the MinIO deployment The attack is deterministic (100% success rate, no race conditions). #### Attack Prerequisites The attacker must know the OIDC `ClientSecret`. While this is a shared credential (not a private key), it is more accessible than commonly assumed: - CVE-2023-28432 previously leaked environment variables including `MINIO_IDENTITY_OPENID_CLIENT_SECRET` - Client secrets are often present in frontend OAuth configurations, mobile app bundles, CI/CD pipelines, and shared configuration files - In many organizations, the client secret is accessible to operators and engineers who should not be able to forge arbitrary identities #### Affected Versions All MinIO releases from `RELEASE.2022-11-08T05-27-07Z` through the final release of the `minio/minio` open-source project. ### Patches **Fixed in:** MinIO AIStor `RELEASE.2026-03-17T21-25-16Z` ## Downloads ### Binary Downloads | Platform | Architecture | Download | | -------- | ------------ | -------------------------------------",
    "evidence": "osv:GHSA-5cx5-wh4m-82fh",
    "products": [
      {
        "name": {
          "value": "github.com/minio/minio",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "GHSA-5cx5-wh4m-82fh",
      "aliases": [
        "CVE-2026-33322",
        "GHSA-5cx5-wh4m-82fh",
        "GO-2026-4779"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "0.0.0-20260212201848-7aac2a2c5b7c"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/minio/minio",
            "purl": "pkg:golang/github.com/minio/minio",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-5cx5-wh4m-82fh/GHSA-5cx5-wh4m-82fh.json"
          }
        }
      ],
      "modified": "2026-10-08T08:11:02.122364367Z",
      "provider": "osv",
      "references": [
        "https://github.com/minio/minio/security/advisories/GHSA-5cx5-wh4m-82fh",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-33322",
        "https://github.com/minio/minio"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-287",
          "CWE-327"
        ],
        "severity": "CRITICAL",
        "github_reviewed": true,
        "nvd_published_at": "2026-03-24T20:16:27Z",
        "github_reviewed_at": "2026-03-19T17:56:37Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-33322",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 98763,
  "published_at": "2026-03-19T17:56:37+00:00"
}