D-Link DIR-605L A1 /bin/telnetd.sh strcmp hard-coded credentials

Summaryinfo

A vulnerability marked as critical has been reported in D-Link DIR-605L A1. Affected by this vulnerability is the function strcmp of the file /bin/telnetd.sh. Performing a manipulation results in hard-coded credentials. This vulnerability only affects products that are no longer supported by the maintainer. This vulnerability is reported as CVE-2026-42372. The attacker must have access to the local network to execute the attack. No exploit exists.

Detailsinfo

A vulnerability was found in D-Link DIR-605L A1 (the affected version is unknown). It has been classified as critical. This affects the function strcmp of the file /bin/telnetd.sh. The manipulation with an unknown input leads to a hard-coded credentials vulnerability. CWE is classifying the issue as CWE-798. The product contains hard-coded credentials, such as a password or cryptographic key, which it uses for its own inbound authentication, outbound communication to external components, or encryption of internal data. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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 -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.

The weakness was disclosed by Arjun Basnet. It is possible to read the advisory at securin.io. This vulnerability is uniquely identified as CVE-2026-42372 since 04/27/2026. The exploitability is told to be easy. The attack needs to be initiated within the local network. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 05/04/2026). The attack technique deployed by this issue is T1110.001 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Router Operating System

Vendor

• D-Link

Name

• DIR-605L A1

License

• commercial

Support

• end of life

Website

• Vendor: https://www.dlink.com/

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