CVE-2026-42372
Published: 04 May 2026
Description
D-Link DIR-605L Hardware Revision A1 (End-of-Life, EOL) contains a hardcoded telnet backdoor. The device starts a telnet daemon at boot via /bin/telnetd.sh with the username "Alphanetworks" and the static password "wrgn35_dlwbr_dir605l" read from /etc/alpha_config/image_sign. The custom telnetd binary accepts a…
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-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.
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Enables users to notice when hard-coded credentials have been exploited for unauthorized access.
Security training explicitly warns against hard-coded credentials, lowering their use in systems.
Policy and procedures prohibit hard-coded credentials in favor of managed authentication.
External identity providers eliminate the need for hard-coded credentials in applications.
Changing default authenticators prior to first use and protecting content prevents use of hard-coded credentials.
Central credential stores and rotation policies remove the need for hard-coded credentials in configuration files or code.
Intelligence programs surface reports of campaigns that abuse hard-coded credentials in products, prompting removal or replacement and thereby reducing successful exploitation.
Planned investment enables secure credential storage and management systems instead of hard-coded credentials.
Security SummaryAI
CVE-2026-42372 is a hardcoded credentials vulnerability (CWE-798) affecting the D-Link DIR-605L Hardware Revision A1 router, an End-of-Life (EOL) device. The flaw involves a telnet backdoor that starts a telnet daemon at boot via the /bin/telnetd.sh script. This daemon uses hardcoded credentials—username "Alphanetworks" and static password "wrgn35_dlwbr_dir605l"—sourced from /etc/alpha_config/image_sign. A custom telnetd binary accepts a -u user:password flag, while the custom login binary employs strcmp() for credential validation. The vulnerability carries a CVSS v3.1 base score of 8.8 (AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
An unauthenticated attacker on the local network (adjacent access) can exploit this backdoor with low complexity and no privileges required. By connecting to the telnet service and supplying the known credentials, the attacker gains a root shell, achieving full administrative control over the device, including high confidentiality, integrity, and availability impacts.
Advisories, including those from Securin.io, confirm the device is EOL and will not receive patches or firmware updates for mitigation. Security practitioners should isolate or decommission affected DIR-605L A1 routers, as no vendor remediation is available. References: https://www.securin.io/zero-day/cve-2026-42372-hardcoded-telnet-backdoor-in-d-link-dir-605l-a1-end-of-life-.
Details
- CWE(s)
AI Security AnalysisAI
- AI Category
- Other AI Platforms
- Risk Domain
- N/A
- OWASP Top 10 for LLMs 2025
- None mapped
- MITRE ATLAS Techniques
- None mapped
- Classification Reason
- Matched keywords: backdoor
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Hardcoded telnet credentials directly enable Valid Accounts (default/backdoor account T1078.001) to access Remote Services (telnet T1021) and obtain a root Unix shell (T1059.004).