CVE-2026-42376

Published: Mag 04, 2026 Last Modified: Mag 04, 2026

ExploitDB:

Other exploit source:

Google Dorks:

CRITICAL 9,8

Source: 33c584b5-0579-4c06-b2a0-8d8329fcab9c

Attack Vector: network

Attack Complexity: low

Privileges Required: none

User Interaction: none

Scope: unchanged

Confidentiality: high

Integrity: high

Availability: high

Description

AI Translation Available

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.

798

Use of Hard-coded Credentials

Draft

Abstraction: Base Structure: Simple

Common Consequences

Security Scopes Affected:

Access Control Integrity Confidentiality Availability Other

Potential Impacts:

Bypass Protection Mechanism Read Application Data Gain Privileges Or Assume Identity Execute Unauthorized Code Or Commands Other

Applicable Platforms

Technologies: ICS/OT, Mobile

Likelihood of Exploit: High

View CWE Details

https://www.securin.io/zero-day/cve-2026-42376-hardcoded-te…

https://www.securin.io/zero-day/cve-2026-42376-hardcoded-telnet-backdoor-in-d-l…