CVE-2026-45557

import socket import struct def build_dns_query(domain): # Construct a simple DNS query for the target domain 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) # Encode domain name query_body = b'' for part in domain.split('.'): query_body += bytes([len(part)]) + part.encode() query_body += b'\x00' # Type and Class (A record, IN class) query_body += struct.pack('!HH', 1, 1) return header + query_body # Example usage to trigger the query # The actual exploit requires a malicious authoritative DNS server # responding with malformed DNSSEC records to the victim server. print("This POC demonstrates the query structure. To exploit CVE-2026-45557,") print("an attacker would set up a malicious authoritative nameserver that returns") print("incomplete RRSIG or mismatched DNSKEY records for the queried domain.") query = build_dns_query('example.com') print(f"Generated DNS Query Packet: {query.hex()}")

{"cve": {"id": "CVE-2026-45557", "sourceIdentifier": "9119a7d8-5eab-497f-8521-727c672e3725", "published": "2026-05-19T15:16:31.640", "lastModified": "2026-05-19T17:57:25.143", "vulnStatus": "Awaiting Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "Technitium DNS Server aggressively tries to fetch missing RRSIG records or mismatched DNSKEY records. An attacker in control of a domain can cause a vulnerable system to generate excessive network traffic. Fixed in 15.0."}], "metrics": {"cvssMetricV40": [{"source": "9119a7d8-5eab-497f-8521-727c672e3725", "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:L/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": "LOW", "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": "9119a7d8-5eab-497f-8521-727c672e3725", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L", "baseScore": 5.8, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 1.4}]}, "weaknesses": [{"source": "9119a7d8-5eab-497f-8521-727c672e3725", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-405"}, {"lang": "en", "value": "CWE-406"}, {"lang": "en", "value": "CWE-770"}]}], "references": [{"url": "https://github.com/TechnitiumSoftware/DnsServer/blo/master/CHANGELOG.md#version-150", "source": "9119a7d8-5eab-497f-8521-727c672e3725"}, {"url": "https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2025/va-26-138-02.json", "source": "9119a7d8-5eab-497f-8521-727c672e3725"}, {"url": "https://www.cve.org/CVERecord?id=CVE-2026-45557", "source": "9119a7d8-5eab-497f-8521-727c672e3725"}]}}