EUVD-2026-27029CVSS VectorNVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
4DescriptionNVD
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.
AnalysisAI
Hardcoded telnet backdoor in D-Link DIR-456U Hardware Revision A1 firmware grants remote unauthenticated attackers root shell access using static credentials ('Alphanetworks' / 'whdrv01_dlob_dir456U'). The telnet daemon launches automatically at boot via /etc/init0.d/S80telnetd.sh and validates credentials through strcmp() comparison against hardcoded values in /etc/config/image_sign. …
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RemediationAI
Within 24 hours: Identify all DIR-456U Hardware Revision A1 devices on the network using asset inventory or network scan; flag for urgent remediation. Within 7 days: Either air-gap affected devices (disconnect from production network) or begin replacement with current-generation routers from D-Link or alternative vendors. …
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