Unity Catalog has a JWT Issuer Validation Bypass Allows Complete User Impersonation

{
  "id": "0d0f087826ea93c71b95adb30ff4c63d8abdfdf16416d8cc501b4de4c3b106ef",
  "url": "https://osv.dev/vulnerability/CVE-2026-27478",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Unity Catalog has a JWT Issuer Validation Bypass Allows Complete User Impersonation",
    "summary": "Unity Catalog is an open, multi-modal Catalog for data and AI. In 0.4.0 and earlier, a critical authentication bypass vulnerability exists in the Unity Catalog token exchange endpoint (/api/1.0/unity-control/auth/tokens). The endpoint extracts the issuer (iss) claim from incoming JWTs and uses it to dynamically fetch the JWKS endpoint for signature validation without validating that the issuer is a trusted identity provider.",
    "evidence": "osv:CVE-2026-27478",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-27478",
      "aliases": [
        "CVE-2026-27478",
        "GHSA-qqcj-rghw-829x"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/unitycatalog/unitycatalog",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "4fa81306825341728580f0ecd2733b58a029e53a"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "0.4.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "cpe": "cpe:2.3:a:unitycatalog:unitycatalog:*:*:*:*:data:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "0.4.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.4.0",
            "ai-v0.3.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-27478.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:37.040313089Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27478.json",
        "https://github.com/unitycatalog/unitycatalog/security/advisories/GHSA-qqcj-rghw-829x",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-27478"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-1390",
          "CWE-290",
          "CWE-346"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27478.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-27478",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 504254,
  "published_at": "2026-03-11T19:36:03.271+00:00"
}