CVE-2026-21265

# CVE-2026-21265 PoC Concept # This PoC demonstrates the certificate update failure scenario # Note: Actual exploitation requires physical access and high privileges import subprocess import struct import datetime def check_secure_boot_status(): """Check if Secure Boot is enabled""" try: result = subprocess.run( ['bcdedit', '/enum', 'all'], capture_output=True, text=True ) return 'secureboot' in result.stdout.lower() except Exception as e: print(f"Error checking Secure Boot status: {e}") return False def check_certificate_expiration(): """Check if Microsoft Secure Boot certificates are expired or expiring soon""" certificates = [ { 'name': 'Microsoft Corporation KEK CA 2011', 'purpose': 'Signs updates to the DB and DBX', 'expiration': datetime.date(2026, 6, 24) }, { 'name': 'Microsoft Corporation UEFI CA 2011', 'purpose': 'Signs 3rd party boot loaders, Option ROMs', 'expiration': datetime.date(2026, 6, 27) }, { 'name': 'Microsoft Windows Production PCA 2011', 'purpose': 'Signs the Windows Boot Manager', 'expiration': datetime.date(2026, 10, 19) } ] current_date = datetime.date.today() vulnerable = [] for cert in certificates: days_until_expiration = (cert['expiration'] - current_date).days if days_until_expiration < 180: # Less than 6 months vulnerable.append({ 'certificate': cert['name'], 'days_remaining': days_until_expiration, 'expiration_date': cert['expiration'].isoformat() }) return vulnerable def simulate_firmware_defect(): """ Simulate the firmware defect that causes certificate update failure. In a real scenario, this would involve manipulating the update process to trigger the firmware bug. """ print("[*] Simulating firmware defect in certificate update mechanism...") print("[*] Attempting to trigger unpredictable behavior in Secure Boot trust chain") print("[!] This would require physical access and high privileges") return { 'status': 'simulated', 'note': 'Real exploitation requires specialized firmware tools and physical access' } if __name__ == '__main__': print("CVE-2026-21265 Analysis Tool") print("=" * 50) if check_secure_boot_status(): print("[+] Secure Boot is enabled") else: print("[-] Secure Boot is not enabled") vulnerable_certs = check_certificate_expiration() if vulnerable_certs: print("\n[!] Found certificates expiring soon:") for cert in vulnerable_certs: print(f" - {cert['certificate']}: {cert['days_remaining']} days remaining") else: print("\n[+] No certificates expiring within 6 months")

{"cve": {"id": "CVE-2026-21265", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:25.053", "lastModified": "2026-01-14T20:23:43.417", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Windows Secure Boot stores Microsoft certificates in the UEFI KEK and DB. These original certificates are approaching expiration, and devices containing affected certificate versions must update them to maintain Secure Boot functionality and avoid compromising security by losing security fixes related to Windows boot manager or Secure Boot.\nThe operating system’s certificate update protection mechanism relies on firmware components that might contain defects, which can cause certificate trust updates to fail or behave unpredictably. This leads to potential disruption of the Secure Boot trust chain and requires careful validation and deployment to restore intended security guarantees.\n\n\n\nCertificate Authority (CA)\nLocation\nPurpose\nExpiration Date\n\n\n\n\nMicrosoft Corporation KEK CA 2011\nKEK\nSigns updates to the DB and DBX\n06/24/2026\n\n\nMicrosoft Corporation UEFI CA 2011\nDB\nSigns 3rd party boot loaders, Option ROMs, etc.\n06/27/2026\n\n\nMicrosoft Windows Production PCA 2011\nDB\nSigns the Windows Boot Manager\n10/19/2026\n\n\n\nFor more information see this CVE and Windows Secure Boot certificate expiration and CA updates."}, {"lang": "es", "value": "Secure Boot de Windows almacena certificados de Microsoft en el KEK y DB de UEFI. Estos certificados originales están próximos a caducar, y los dispositivos que contienen versiones de certificados afectadas deben actualizarlos para mantener la funcionalidad de Secure Boot y evitar comprometer la seguridad al perder las correcciones de seguridad relacionadas con el gestor de arranque de Windows o Secure Boot.\nEl mecanismo de protección de actualización de certificados del sistema operativo se basa en componentes de firmware que podrían contener defectos, lo que puede hacer que las actualizaciones de confianza de los certificados fallen o se comporten de manera impredecible. Esto lleva a una posible interrupción de la cadena de confianza de Secure Boot y requiere una validación y un despliegue cuidadosos para restaurar las garantías de seguridad previstas.\n\nAutoridad de Certificación (CA)\nUbicación\nPropósito\nFecha de Vencimiento\n\nMicrosoft Corporation KEK CA 2011\nKEK\nFirma las actualizaciones de la DB y DBX\n24/06/2026\n\nMicrosoft Corporation UEFI CA 2011\nDB\nFirma cargadores de arranque de terceros, ROMs de opción, etc.\n27/06/2026\n\nMicrosoft Windows Production PCA 2011\nDB\nFirma el Gestor de Arranque de Windows\n19/10/2026\n\nPara más información, consulte este CVE y el vencimiento de los certificados de Secure Boot de Windows y las actualizaciones de CA."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H", "baseScore": 6.4, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "HIGH", "privilegesRequired": "HIGH", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 0.5, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-1329"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x64:*", "versionEndExcluding": "10.0.14393.8783", "matchCriteriaId": "9A956D23-259E-450B-8406-FEB2BBED1F39"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*", "versionEndExcluding": "10.0.14393.8783", "matchCriteriaId": "41D387B9-5E9D-47CB-B044-D7D10FFFB458"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:*", "versionEndExcluding": "10.0.17763.8276", "matchCriteriaId": "DD4CBDAB-7626-4048-8474-B1BD9C1F3255"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*", "versionEndExcluding": "10.0.17763.8276", "matchCriteriaId": "A6D4C631-2CC0-407C-9ACA-7C151006598C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:arm64:*", "versionEndExcluding": "10.0.19044.6809", "matchCriteriaId": "9CFC3200-1FAB-4AB1-A008-F703EEF3505A"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x64:*", "versionEndExcluding": "10.0.19044.6809", "matchCriteriaId": "E481E93D-D86E-4B65-93E5-200327C348C8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x86:*", "versionEndExcluding": "10.0.19044.6809", "matchCriteriaId": "F720EC9F-6A33-445F-AFA1-794405737E57"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:arm64:*", "versionEndExcluding": "10.0.190 ... 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